Zinc-dependent Enzymes Research Articles

Role of MMPs in connective tissue breakdown and periodontal disease: A Review

Matrix metalloproteinases (MMPs) are a group of zinc-dependent enzymes that play a critical role in the degradation of extracellular matrix components, including collagen, elastin, and proteoglycans, making them central to tissue remodeling processes. In the context of periodontal disease, MMPs are key mediators of connective tissue breakdown and alveolar bone destruction, driven by chronic inflammation. This review focuses on the role of MMPs in periodontal disease, highlighting their regulation, activation mechanisms, and the interplay with inflammatory cytokines such as interleukins and tumor necrosis factor-alpha (TNF-α). Furthermore, the review discusses the contribution of specific MMPs, including MMP-1, MMP-8, and MMP-9, in periodontal tissue degradation and explores potential therapeutic approaches to inhibit MMP activity to prevent periodontal disease progression. By understanding the molecular basis of MMP involvement in periodontal pathology, this review aims to provide insights into novel therapeutic strategies aimed at mitigating connective tissue breakdown in periodontal disease.

Targeting metallo-β-lactamase inhibition with Schiff bases of 4-amino-1,2,4-triazole-3-thione: In silico docking, molecular dynamics, and pharmacological assessments

Metallo-β-lactamases are zinc-dependent enzymes that hydrolyze and inactivate a wide range of β-lactam antibiotics, including penicillins, cephalosporins, and carbapenems, making them a significant factor in bacterial resistance. Therefore, developing inhibitors targeting metallo-β-lactamases is crucial for combating antibiotic resistance in Gram-negative bacteria and restoring the effectiveness of these essential antimicrobial agents. This study focuses on the synthesis, in silico docking, molecular dynamics simulations, and biological evaluation of twenty-one Schiff base analogs (6a–u) derived from trans-4-amino-5-(4-(4-chlorophenyl)cyclohexyl)-1,2,4-triazole-3-thione. Molecular docking studies were carried out on the New Delhi metallo-β-lactamase-1 active sites of Klebsiella pneumoniae (PDB: 5N0H) and Escherichia coli (PDB: 6KXI) to evaluate the binding interactions between the thiolate form of ligands and zinc ions. Docking analysis reveals that the synthesized analogs are stably positioned in the NDM-1 active site, aligning closely with zinc ions. The zinc ions in the active binding site coordinate with the nitrogen atoms of the triazole ring and the thiolate anion. Molecular Dynamics Simulations confirmed the stability of the protein-ligand complexes, demonstrating that the ligands maintained optimal positioning within the active site with minimal fluctuations in surrounding residues. The in vitro antibacterial activity of these analogs was evaluated at concentrations of 4 mg/L and 8 mg/L in combination with meropenem against various carbapenem-resistant Gram-negative isolates expressing NDM-1, Class A (SHV, TEM), or Class C (CMY) β-lactamases. The results indicated modest potentiation of meropenem's antibacterial activity, with a 2–3 fold increase in efficacy when used alongside the Schiff base analogs. Notably, two analogs emerged as significant hits in this study.

MMP9 gene expression alterations in gastric cancer and their role in cell migration

Background. Gastric cancer (GC) is a significant global health concern, ranking as the fifth most common malignant tumor and the fourth leading cause of cancer-related deaths worldwide. The primary treatment approach for metastatic GC is systemic chemotherapy. Matrix metalloproteinases (MMPs) are a group of zinc-dependent proteolytic enzymes that play crucial roles in various physiological processes. Among them, MMP9 is known for its complexity and its ability to degrade the components of the extracellular matrix. This study aimed to compare the expression of the MMP9 gene in cancerous and adjacent tissue of GC and evaluate its knockdown effects on GC cell line migration. Methods. In the present study, 50 tumor tissues and adjacent non-tumor control tissues were collected from patients with GC. Using a real-time polymerase chain reaction, the expression levels of the MMP9 gene were assessed in these samples. Additionally, bioinformatics methods were employed to analyze MMP9 expression in a larger cohort of GC patients. Furthermore, a data mining study was conducted to investigate the potential impact of MMP9 expression on the overall survival of GC patients. In addition, appropriate small interfering RNA (siRNA) was synthesized to suppress the MMP9 oncogene and transfected into the GC cell line, and migration was investigated eventually. Results. The results demonstrated significant upregulation of the MMP9 gene in tumor samples compared to tumor-adjacent samples, with a notable fold change of 4.6. This consistent finding was further supported by our bioinformatics analysis. Additionally, our pan-cancer analysis of TCGA data revealed that MMP9 is upregulated in various malignant tumors, indicating its potential relevance beyond GC. After MMP9 siRNA transfection, the migration rate of the cancer cells was evaluated by a wound-healing assay. The GC cell migration and invasion significantly decreased after the knockdown of MMP9 by specific siRNA. Conclusion. In general, our study showed MMP9 upregulation in GC and suggested that the transfection of MMP9 gene siRNA could reduce invasion and migration. Practical Implications. siRNAs are promising medical breakthroughs for the treatment of MMP9-related cancer invasion and migration. However, there is still a need to deepen our understanding of MMP9 gene function in tumorigenesis.

The influence of zinc levels on osteoarthritis: A comprehensive review

Abstract Osteoarthritis (OA), a disease with a multifactorial aetiology and an enigmatic root cause, affects the quality of life of many elderly patients. Even though there are certain medications utilised to reduce the symptomatic effects, a reliable treatment method to reverse the disease is yet to be discovered. Zinc is a cofactor of over 3000 proteins and is the only metal found in all six classes of enzymes. We explored zinc’s effect on the immune system and the bones as OA affects both. We also discussed zinc-dependent enzymes, highlighting their significant role in the disease’s pathogenesis. It is important to note that both excessive and deficient zinc levels can negatively affect bone health and immune function, thereby exacerbating OA. The purpose of this review is to offer a better understanding of zinc’s impact on OA pathogenesis and to provide clarity regarding its beneficial and detrimental outcomes. We searched thoroughly systematic reviews, meta-analysis, review articles, research articles and randomised controlled trials to ensure a comprehensive review. In brief, using zinc supplementation in the treatment of OA may act as a doubled-edged sword, offering potential benefits but also posing risks.

Rate of hydrolysis of the phosphate esters of B vitamins is reduced by zinc deficiency: Invitro and invivo.

Extracellular hydrolysis of the phosphate esters of B vitamins (B1, B2, and B6) is crucial for their cellular uptake and metabolism. Although a few zinc-dependent enzymes have been implicated in these processes, their exact mechanisms of action remain largely unknown. This study investigated the potential involvement of phosphate group hydrolyzing enzymes in the hydrolysis of B vitamin phosphate esters. We evaluated enzyme activity in membrane lysates prepared from cells transiently transfected with these enzymes or those endogenously expressing them. Specifically, we investigated how zinc deficiency affects the rate of hydrolysis of B vitamin phosphate esters in cellular lysates. Assessment of the activities of zinc-dependent ectoenzymes in the lysates prepared from cells cultured in zinc-deficient conditions and in the serum of rats fed zinc-deficient diets revealed that zinc deficiency reduced the extracellular hydrolysis activity of B vitamin phosphate esters. Furthermore, our findings explain the similarities between several symptoms of B vitamin and zinc deficiencies. Collectively, this study provides novel insights into the diverse symptoms of zinc deficiency and could guide the development of appropriate clinical strategies.

Discovery of 2-Aminothiazole-4-carboxylic Acids as Broad-Spectrum Metallo-β-lactamase Inhibitors by Mimicking Carbapenem Hydrolysate Binding.

Metallo-β-lactamases (MBLs) are zinc-dependent enzymes capable of hydrolyzing all bicyclic β-lactam antibiotics, posing a great threat to public health. However, there are currently no clinically approved MBL inhibitors. Despite variations in their active sites, MBLs share a common catalytic mechanism with carbapenems, forming similar reaction species and hydrolysates. We here report the development of 2-aminothiazole-4-carboxylic acids (AtCs) as broad-spectrum MBL inhibitors by mimicking the anchor pharmacophore features of carbapenem hydrolysate binding. Several AtCs manifested potent activity against B1, B2, and B3 MBLs. Crystallographic analyses revealed a common binding mode of AtCs with B1, B2, and B3 MBLs, resembling binding observed in the MBL-carbapenem product complexes. AtCs restored Meropenem activity against MBL-producing isolates. In the murine sepsis model, AtCs exhibited favorable synergistic efficacy with Meropenem, along with acceptable pharmacokinetics and safety profiles. This work offers promising lead compounds and a structural basis for the development of potential drug candidates to combat MBL-mediated antimicrobial resistance.

Transcriptional Response of Burkholderia cenocepacia H111 to Severe Zinc Starvation.

Burkholderia cenocepacia is an opportunistic pathogen that is primarily associated with severe respiratory infections in people with cystic fibrosis. These bacteria have significant intrinsic resistance to antimicrobial therapy, and there is a need for more effective treatments. Bacterial zinc uptake and homeostasis systems are attractive targets for new drugs, yet our understanding of how bacteria acquire and utilise zinc remains incomplete. Here we have used RNA-sequencing and differential gene expression analysis to investigate how B. cenocepacia H111 is able to survive in zinc poor environments, such as those expected to be encountered within the host. The data shows that 201 genes are significantly differentially expressed when zinc supply is severely limited. Included in the 85 upregulated genes, are genes encoding a putative ZnuABC high affinity zinc importer, two TonB-dependent outer membrane receptors that may facilitate zinc uptake across the outer cell membrane, and a COG0523 family zinc metallochaperone. Amongst the 116 downregulated genes, are several zinc-dependent enzymes suggesting a mechanism of zinc sparring to reduce the cells demand for zinc when bioavailability is low.

Contents of matrix metalloproteinase type 2 (MMP-2) and complexes MMP-9/TIMP-1, MMP-2/TIMP-2, and total cholesterol in practically healthy people and patients with hypertension

Arterial hypertension (AH) is the most common age-associated disease among the working population. Polyetiology of AH requires a more thorough definition and study of its predictors aiming for understanding the role of external influences, as well as detection of genetic polymorphisms at early stages, in order to limit their implementation. The scientific reviews discuss the important role of abnormal vascular remodeling in the pathogenesis of hypertension. The main factor of such alterations is the rearrangement of extracellular matrix due to matrix metalloproteinases (MMP), the zinc-dependent enzymes with a wide substrate specificity. In addition, in more than 70% of cases, AH is combined with lipid metabolism disorders, including an increase in cholesterol levels. These mechanisms should be taken into account when assessing risk factors for development of cardiovascular accidents. The role of MMP-2 and the complexes MMP- 9/ TIMP- 1, MMP-2/TIMP-2 in pathogenesis of vascular restructuring is insufficiently described in the review articles. The article presents our results of studying the system of proteolytic enzymes and the level of total cholesterol in 110 practically healthy people and 90 persons with AH aged 18 to 74 years old. The levels of MMP-2, MMP-9/ TIMP- 1, MMP-2/TIMP-2 complexes in blood serum were studied by the sandwich variant of ELISA technique. Statistical processing of the obtained data was carried out using the analytical software IBM SPSS Statistics, v. 22.0.1. It was found that in the groups of women, regardless of the presence, or absence of pathology, the level of total cholesterol is higher if compared with male subjects. MMP-2 values were low both in the general group of practically healthy people, regardless of gender, and in the group of men with hypertension. Proteolytic activity of MMP-2 shows a broader substrate activity in women with hypertension. In the group of practically healthy men and women, we have registered lower levels of the studied MMP complexes and their tissue inhibitors. An imbalance in the proteolysis/antiproteolysis system is observed both in the group of hypertensive women with more pronounced effects upon migration, proliferation and apoptosis of smooth muscle cells, endothelial and inflammatory cells, thus determining formation of intima and arterial remodeling, as well as in the group of men with hypertension with predominance of remodeling factors that affects the rigidity of vascular wall.

Metalloproteases in Pain Generation and Persistence: A Possible Target?

Matrix metalloproteinases (MMPs) are a large family of zinc-dependent proteolytic enzymes associated with extracellular matrix protein turnover and tissue degradation. They participate to many different physiological reactions but are also hyperactivated in several diseases. Various literature studies have documented that MMPs play a role in the modulation of neuropathic and nociceptive pain. The heterogeneity of clinical and pre-clinical data is an important issue in this experimental context. Despite the presence of a good number of studies on MMP inhibitors, these drugs showed scarce efficacy and relevant side effects. In the present manuscript, we reviewed studies in the literature that define a possible role of MMPs in pain and the effects of their modulation.

Isolation and Characterization of NpCI, a New Metallocarboxypeptidase Inhibitor from the Marine Snail Nerita peloronta with Anti-Plasmodium falciparum Activity

Metallocarboxypeptidases are zinc-dependent peptide-hydrolysing enzymes involved in several important physiological and pathological processes. They have been a target of growing interest in the search for natural or synthetic compound binders with biomedical and drug discovery purposes, i.e., with potential as antimicrobials or antiparasitics. Given that marine resources are an extraordinary source of bioactive molecules, we screened marine invertebrates for new inhibitory compounds with such capabilities. In this work, we report the isolation and molecular and functional characterization of NpCI, a novel strong metallocarboxypeptidase inhibitor from the marine snail Nerita peloronta. NpCI was purified until homogeneity using a combination of affinity chromatography and RP-HPLC. It appeared as a 5921.557 Da protein with 53 residues and six disulphide-linked cysteines, displaying a high sequence similarity with NvCI, a carboxypeptidase inhibitor isolated from Nerita versicolor, a mollusc of the same genus. The purified inhibitor was determined to be a slow- and tight-binding inhibitor of bovine CPA (Ki = 1.1·× 10-8 mol/L) and porcine CPB (Ki = 8.15·× 10-8 mol/L) and was not able to inhibit proteases from other mechanistic classes. Importantly, this inhibitor showed antiplasmodial activity against Plasmodium falciparum in an in vitro culture (IC50 = 5.5 μmol/L), reducing parasitaemia mainly by inhibiting the later stages of the parasite's intraerythrocytic cycle whilst having no cytotoxic effects on human fibroblasts. Interestingly, initial attempts with other related proteinaceous carboxypeptidase inhibitors also displayed similar antiplasmodial effects. Coincidentally, in recent years, a metallocarboxypeptidase named PfNna1, which is expressed in the schizont phase during the late intraerythrocytic stage of the parasite's life cycle, has been described. Given that NpCI showed a specific parasiticidal effect on P. falciparum, eliciting pyknotic/dead parasites, our results suggest that this and related inhibitors could be promising starting agents or lead compounds for antimalarial drug discovery strategies.

Research Progress on Mechanism and Application of Zinc in Osteogenesis

As the second most abundant trace metal element in the human body, zinc plays an important role in bone homeostasis and bone disease treatment. Adequate amounts of zinc not only mediates osteogenesis-related pathways through zinc dependent enzymes and zinc finger proteins to induce the differentiation of mesenchymal stem cells into osteoblasts and promote osteogenesis, but also inhibits osteoclast resorption activity, reducing bone resorption and thus promoting osteogenesis. In recent years, the importance of zinc in bone development, regeneration and homeostasis has been gradually discovered. The mechanism and application of zinc's osteogenic effect have been extensively studied. The aim of this paper is to summarize the research on zinc osteogenic mechanism and review its application research in bone tissue engineering in recent years.

Matrix Metalloproteinases in Oral Cancer

Zinc-dependent proteolytic enzymes known as matrix metalloproteinases (MMPs) are a class of structurally related enzymes that are known to be crucial in the catabolic turnover of extracellular matrix (ECM) components. MMPs are thought to control the activity of a number of non-ECM bioactive substrates, such as growth factors, cytokines, chemokines, and cell receptors, which control the tissue microenvironment. The interaction between cells and ECM plays a key role in normal development and differentiation of organism and many pathological states as well. The primary class of controlling proteases in the ECM is known as MMPs. Aspects of normal physiology and pathology depend on the ability of MMPs to change the structural integrity of tissues. Uncontrolled ECM turnover, tissue remodeling, inflammatory response, cell proliferation, and migration are pathogenic alterations that can result from an imbalance between the concentration of active metalloproteinases and their inhibitors (tissue inhibitors of metalloproteinases [TIMPs]). This detailed review provides some information on the function of MMPs in inflammatory, caries and periapical, cancer, and other oral diseases. Blood and saliva are the two biological fluids that are most frequently used to diagnose oral disorders. Most of the ECM components in patients undergo digestion to lower molecular weight forms, resulting in much higher amounts of MMPs in their saliva/blood than in healthy individuals. Conventional treatment successfully reduces the levels of MMPs which inhibits the progressive breakdown of collagens in ECM components.

Neuro-Axonal Damage and Alteration of Blood-Brain Barrier Integrity in COVID-19 Patients.

Neurofilament light chain (NfL) is a specific biomarker of neuro-axonal damage. Matrix metalloproteinases (MMPs) are zinc-dependent enzymes involved in blood–brain barrier (BBB) integrity. We explored neuro-axonal damage, alteration of BBB integrity and SARS-CoV-2 RNA presence in COVID-19 patients with severe neurological symptoms (neuro-COVID) as well as neuro-axonal damage in COVID-19 patients without severe neurological symptoms according to disease severity and after recovery, comparing the obtained findings with healthy donors (HD). Overall, COVID-19 patients (n = 55) showed higher plasma NfL levels compared to HD (n = 31) (p < 0.0001), especially those who developed ARDS (n = 28) (p = 0.0005). After recovery, plasma NfL levels were still higher in ARDS patients compared to HD (p = 0.0037). In neuro-COVID patients (n = 12), higher CSF and plasma NfL, and CSF MMP-2 levels in ARDS than non-ARDS group were observed (p = 0.0357, p = 0.0346 and p = 0.0303, respectively). SARS-CoV-2 RNA was detected in four CSF and two plasma samples. SARS-CoV-2 RNA detection was not associated to increased CSF NfL and MMP levels. During COVID-19, ARDS could be associated to CNS damage and alteration of BBB integrity in the absence of SARS-CoV-2 RNA detection in CSF or blood. CNS damage was still detectable after discharge in blood of COVID-19 patients who developed ARDS during hospitalization.

Regulation of zinc-dependent enzymes by metal carrier proteins.

Zn2+ ions are essential in many physiological processes, including enzyme catalysis, protein structural stabilization, and the regulation of many proteins. The affinities of proteins for Zn2+ ions span several orders of magnitude, with catalytic Zn2+ ions generally held more tightly than structural or regulatory ones. Metal carrier proteins, most of which are not specific for Zn2+, bind these ions with a broad range of affinities that overlap those of catalytic, structural, and regulatory Zn2+ ions and are thought to be responsible for distributing the metal through most cells, tissues, and fluid compartments. While little is known about how many proteins obtain or release these ions, there is now considerable experimental evidence suggesting that metal carrier proteins may be responsible for transferring metals to and from some Zn2+-dependent proteins, thus serving as a major regulatory factor for them. In this review, the biological roles of Zn2+ and structures of Zn2+ binding sites are examined, and experimental evidence demonstrating the direct participation of metal carrier proteins in enzyme regulation is discussed. Mechanisms of metal ion transfer are also offered, and the potential physiological significance of this phenomenon is explored.

Histone deacetylase 1 in patients with alopecia areata and acne vulgaris: An epigenetic alteration.

Histone deacetylase 1 (HDAC1) belongs to class I histone deacetylases, which are zinc-dependent enzymes that remove the acetyl group from histones and other proteins providing epigenetic regulation of gene expression. It plays an important role in the hair follicle and epidermal homeostasis in addition to its immunomodulatory roles. Alopecia areata (AA) and acne vulgaris are common skin diseases in which epigenetic factors have been proposed. However, studies of epigenetic modifications in both diseases are quite limited. This study aimed at elucidation of HDAC1 deregulation in AA and acne vulgaris. A case-control study was conducted on 76 participants: 25 patients with patchy alopecia areata, 26 patients with acne vulgaris and 25 healthy controls. Blood samples were collected for the measurement of HDAC1 level by ELISA. A significant difference in the serum level of HDAC1 was found between the studied groups being highest in the AA group (P = 0.0001). It was significantly higher in the AA group than the acne vulgaris group (P = 0.0001). HDAC1 appears to be deregulated in patients with AA and acne vulgaris. This may suggest a potential therapeutic opportunity for HDAC inhibitors for the treatment of such diseases.

LAM-1 from Lysobacter antibioticus: A potent zinc-dependent activity that inactivates β-lactam antibiotics

Resistance to β-lactam antibiotics, including the “last-resort” carbapenems, has emerged as a major threat to global health. A major resistance mechanism employed by pathogens involves the use of metallo-β-lactamases (MBLs), zinc-dependent enzymes that inactivate most of the β-lactam antibiotics used to treat infections. Variants of MBLs are frequently discovered in clinical environments. However, an increasing number of such enzymes have been identified in microorganisms that are less impacted by human activities. Here, an MBL from Lysobacter antibioticus, isolated from the rhizosphere, has been shown to be highly active toward numerous β-lactam antibiotics. Its activity is higher than that of some of the most effective MBLs linked to hospital-acquired antibiotic resistance and thus poses an interesting system to investigate evolutionary pressures that drive the emergence of such biocatalysts.

Marginal Zinc Deficiency in Mice Increased the Number of Abnormal Sperm and Altered the Expression Level of Spermatogenesis-Related Genes

Marginal zinc deficiency is more common than severe zinc deficiency, and the effect of marginal zinc deficiency on male reproduction is unknown. This study investigated the effect of marginal zinc deficiency on spermatogenesis and its mechanism. Male ICR mice were fed normal zinc (30mg/kg) and marginal zinc deficiency (10mg/kg) diets for 35days. Zinc-dependent proteins and enzymes were measured as biomarkers of zinc levels in the body. Metallothionein and Cu-Zn SOD levels in the control group were higher than those in the marginal zinc deficiency group. Hematoxylin and eosin staining showed that the marginal zinc deficiency diet caused histopathological changes in the testis and destruction of the sperm head under scanning electron microscopy. Sperm parameters and sex hormone levels were also affected by marginal zinc deficiency. In addition, marginal zinc deficiency led to alter expression level of several important spermatogenesis-related genes in the epididymis and testes. These results indicate that although zinc intake in marginal zinc deficiency is close to the recommended reference value, low zinc intake interferes with the expression of genes related to spermatogenesis and may lead to sperm abnormalities in mice.

The role of micronutrient and immunomodulation effect in the vaccine era of COVID-19.

Different dietary nutrients have distinct effects, including enhancing immune response activity and supporting mucous membrane integrity. These effects are critical in fighting against pathogenic agents, which cover coronavirus disease 2019 (COVID-19), the coronavirus disease that shuts down globally. Recent researches have shown that micronutrient deficiency is commonly associated with compromised immune responses, respiratory tract infections, or even susceptibility to COVID-19. The relationship between Vit A and infection is its role in mucosal epithelium integrity (skin and mucous membrane), the supplementation could be an option for assisted-treating the SARS-CoV-2 virus and a possible prevention of lung infection. Vit C/ascorbic acid stimulates oxygen radical scavenging activity of the skin and enhances epithelial barrier function. Ascorbic acid alone or with other natural compounds (baicalin and theaflavin) may inhibit the expression of angiotensin-converting enzyme II in human small alveolar epithelial cells and limited the entry of SARS-CoV-2. Vitamin D receptors can be expressed by immune cells, and different immune cells (macrophages, monocytes, dendritic cells, T cells, and B cells) can convert Vit D into its active form 1,25-(OH)2 D. Oral vitamin D intake can be a readily way to restrict the viral infection through downregulation of ACE2 receptor and to attenuate the disease severity by decreasing the frequency of cytokine storm and pulmonary pro-inflammatory response. Vit E supports T-cell mediated functions, optimization of Th1 response, and suppression of Th2 response. Vitamin E supplementation can lower the production of superoxides and may favors the antioxidants and benefit the progress of COVID-19 treatment. Zinc plays an essential role in both innate and adaptive immune systems and cytokine production, and Zinc-dependent viral enzymes to initiate the infectious process have proved the Zinc levels are directly associated with symptoms relieved of COVID-19. Iron is an essential component of enzymes involved in the activation of immune cells, lower iron levels predispose to severe symptoms of SARS-CoV-2, and monitoring the status can predict the disease severity and mortality. Selenium participates in the adaptive immune response by supporting antibody production and development. Deficiency can reduce antibody concentration, decreased cytotoxicity of NK cells, compromised cellular immunity, and an attenuated response to vaccination. The COVID-19 vaccines including three broad categories, protein-based vaccines, gene-based vaccines (mRNA vaccines and DNA vaccines), combination of gene and protein-based vaccines. Micronutrients are involved in immunity from the virus entering the human to innate immune response and adaptive immune response. Micronutrients are indispensable in immune response of vaccination.

Mechanistic Investigations of Metallo‐β‐lactamase Inhibitors: Strong Zinc Binding Is Not Required for Potent Enzyme Inhibition**

Metallo‐β‐lactamases (MBLs) are zinc‐dependent bacterial enzymes that inactivate essentially all classes of β‐lactam antibiotics including last‐resort carbapenems. At present there are no clinically approved MBL inhibitors, and in order to develop such agents it is essential to understand their inhibitory mechanisms. Herein, we describe a comprehensive mechanistic study of a panel of structurally distinct MBL inhibitors reported in both the scientific and patent literature. Specifically, we determined the half‐maximal inhibitory concentration (IC50) for each inhibitor against MBLs belonging to the NDM and IMP families. In addition, the binding affinities of the inhibitors for Zn2+, Ca2+ and Mg2+ were assessed by using isothermal titration calorimetry (ITC). We also compared the ability of the different inhibitors to resensitize a highly resistant MBL‐expressing Escherichia coli strain to meropenem. These investigations reveal clear differences between the MBL inhibitors studied in terms of their IC50 value, metal binding ability, and capacity to synergize with meropenem. Notably, our studies demonstrate that potent MBL inhibition and synergy with meropenem are not explicitly dependent on the capacity of an inhibitor to strongly chelate zinc.

Deciphering the genetic alterations in matrix metallo-proteinase gene family and its putative association with head and neck squamous cell carcinoma.

Matrix metallo-proteinases (MMPs) a group of zinc-dependent proteolytic enzymes which play a key role in tumorigenesis by degrading almost all extracellular matrix (ECM) components. MMPs are associated with tumour progression including invasion, angiogenesis, metastasis and poor prognosis. Genetic alterations such as single nucleotide variations and other gross chromosomal abnormalities have been found to drive the process of malignant transformation. In line with the above facts, the present study aims to analyse the genetic alterations, associated gene expression patterns and survival probability of HNSCC patients upon differential expression of the crucial members of the MMP family. The observational study utilised several computational tools. The cBioportal database was used as the primary source of identification of genetic alterations in the MMP family of genes. The Cancer Gene Atlas dataset (Firehose Legacy) was used for the investigations. The highest frequency of alteration was identified in the MMP20 gene (8%). The common gene alterations were amplifications, deep deletions, mis-sense and truncating mutations. Interestingly, amplification and deep deletion followed the same pattern in about 31 patients, in genes MMP1, 3, 7, 8, 10, 12, 20, and 27. The MMP20 gene expression analysis showed a significant difference between the normal subjects and the patients with primary tumors (6.95 x 10-4). The Kaplan-Meier survival curve analysis identified that female patients with high-level expression of the MMP20 gene had a low survival probability when compared to male HNSC patients. Taken together, the present study provides preliminary information about the involvement of the MMP20 gene of the MMP family with HNSCC. Further experimental analysis is required to derive a strong association between the gene alterations observed with HNSCC.