Phosphohexose Isomerase Activity Research Articles

The role of respiratory metabolism in chilling injury development of Chinese olive fruit during cold storage

Chilling injury (CI) and browning occurrence are pivotal issues during the cold storage of postharvest Chinese olive fruit. This study evaluates the effects of non-chilling temperature (8 °C) and chilling temperature (2 °C) on CI development, browning occurrence, and respiratory metabolism in postharvest Chinese olives. Compared to storage at 8 °C, storage at 2 °C significantly induced CI, accompanied by higher indices of CI and browning, as well as a higher fruit respiratory rate. Storage at 2 °C increased the activities of phosphohexose isomerase (PGI), succinate dehydrogenase (SDH), ascorbic acid oxidase (AAO), and cytochrome C oxidase (CCO) by 55.1%, 11.1%, 26.4%, and 98.8%, respectively, on day 120. On the other hand, storage at 2 °C reduced the activities of NAD kinase (NADK), 6-phosphogluconate dehydrogenase (6-PGDH) + glucose-6-phosphate dehydrogenase (G-6-PDH) by 95.6% and 6.6%, respectively, on day 120. The contents of nicotinamide adenine dinucleotide (NAD) and its reduced form of NAD (NADH) increased by 10.0% and 22.8%, respectively, in fruit stored at 2 °C on day 120. Conversely, the contents of nicotinamide adenine dinucleotide phosphate (NADP) and its reduced form (NADPH) decreased by 58.3% and 64.4%, respectively, in fruit stored 2 °C on day 120. These findings indicate that CI development and browning occurrence in Chinese olives induced by storage at 2 °C were associated with a higher respiratory rate, increased activities of PGI, SDH, AAO, and CCO, higher contents of NAD(H), reduced activities of 6-PGDH + G-6-PDH, and lower contents of NADP(H).

Alternaria alternata stimulates blackhead disease development of ‘Korla’ fragrant pear (Pyrus bretschneideri Rehd) by regulating energy status and respiratory metabolism

Blackhead disease of ‘Korla’ fragrant pear (Pyrus bretschneideri Rehd), caused by the fungus Alternaria alternata (A. alternata), limits postharvest pear fruit storage and transportation. Herein, we explored the effects of A. alternata infection on respiratory metabolism and energy status of pear fruit, and their correlations with disease development. Compared with control fruit, A. alternata-inoculated fruit displayed a higher respiration rate and disease index. Infection increased the gene expression and enzyme activities of phosphohexose isomerase (PGI), alternative oxidase (AOX), succinate dehydrogenase (SDH) and cytochrome C oxidase (CCO) in pear fruit, and decreased those of 6-phosphogluconate dehydrogenase (6PGDH) and glucose-6-phosphate dehydrogenase (G6PDH) in the late storage period. Infection reduced nicotinamide adenine dinucleotide kinase (NADK) activity and expression level in fruit, inhibited NADP accumulation, and increased NAD, NADH, and NADPH contents in the early storage period. Infection also lowered adenosine triphosphate (ATP), adenosine diphosphate (ADP) and energy charge (EC) levels as well as ATPase activity, and enhanced adenosine monophosphate (AMP) content and PbAtpB expression levels, resulting in decreased fruit energy status. All these results suggest that disease development may be connected to the enhancement of the Embden-Meyerhof-Parnas (EMP) pathway, the tricarboxylic acid (TCA) cycle, the cytochrome pathway (CCP), the alternative pathway (AP), the increased then decrease in the pentose phosphate pathway (PPP), and reduced energy status in pear fruit.

Exogenous nitric oxide inhibits the respiratory metabolism of postharvest wax apple fruit and its role in the delayed cottony softening

This study investigated the impacts of nitric oxide (NO) fumigation on the respiratory metabolism of postharvest wax apple fruit and its impact on fruit cottony softening. NO treatment inhibited the respiration rate of wax apple fruit and delayed the development of cottony softening; NO treatment suppressed the activities of hexokinase, phosphohexose isomerase (PGI), pyruvate dehydrogenase, and succinate dehydrogenase (SDH) in fruit pulp, but improved the activities of pyruvate kinase and citrate synthase (CS), and maintained the contents of glucose and pyruvic acid, indicating a reduction in the EMP-TCA pathway. Moreover, the NADH content and the activities of SDH and cytochrome C oxidase (CCO) were decreased with NO treatment, while the NADH/NAD ratio increased, suggesting that the electron transport chain complexes of wax apple fruit were reduced. Besides, NO treatment enhanced the activity of NADK in wax apple fruit, which lowered the levels of NAD and NADH but increased levels of NADP and NADPH, indicating an increase in pentose phosphate pathway. Additionally, CATPCA and heatmap analysis show that the PGI, CS, SDH, and CCO played a crucial role in NO-inhibited respiration. Collectively, these findings indicate that NO treatment suppressed the respiratory metabolism of postharvest wax apple fruit via regulating respiratory pathways, which reduces fruit senescence and delays cottony softening.

Energy status regulated umami compound metabolism in harvested shiitake mushrooms (Lentinus edodes) with spores triggered to release

The molecular mechanisms of energy status related to the umami taste of postharvest shiitake mushrooms during spore release remain poorly understood. In this study, the variations of energy status and umami taste of mushrooms were measured at 25 °C. At 24 h storage, slight spore prints of mushrooms were first pictured, respiration peaked. Significant ATP decrease and ADP increase were also observed as the initiation of postharvest senescence (P < 0.05). Meanwhile, the activities of phosphohexose isomerase, succinate dehydrogenase, glucose-6-phosphate dehydrogenase and cytochrome c oxidase and the contents of umami nucleotides and amino acids were maintained at higher levels in mushrooms with spore release. Notably, the equivalent umami concentration (EUC) was strongly correlated with energy levels (R = 0.80). Fifteen related gene expression levels in the energy metabolism pathway were downregulated. LecpdP1 and LeAK were significantly expressed in the conversion of ATP into AMP and played key roles in connecting the energy state and umami level. These results provided valuable insights on the umami taste associated with energy metabolism mechanism during postharvest mushroom spore release.

Exogenous melatonin maintains leaf quality of postharvest Chinese flowering cabbage by modulating respiratory metabolism and energy status

The efficacy of melatonin on postharvest quality of Chinese flowering cabbage was investigated in this study. Treatment of Chinese cabbage with melatonin significantly delayed leaf yellowing and maintained higher contents of nutrients such as soluble sugars, protein, vitamin C, total flavonoids and phenols during a 7-day storage. Also, melatonin enhanced the activities and expression level of glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6-PGDH). Melatonin treatment decreased tissue weight loss, respiration rate, activities of phosphohexose isomerase (PHI), succinate dehydrogenase (SDH), cytochrome C oxidase (CCO), and ascorbic acid oxidase (AAO) and the expression of their corresponding genes. Additionally, melatonin-treated leaves maintained high energy status, as evidenced by higher total ATPase and nicotinamide adenine dinucleotide kinase (NADK) activities, higher energy charge level, adenosine triphosphate (ATP) and adenosine diphosphate (ADP) contents, lower level of adenosine monophosphate (AMP) and transcript abundance of respiratory enzymes. These findings collectively suggest that melatonin maintains leaf quality of postharvest Chinese flowering cabbage might be, at least in part, due to the reduced ratio of Embden-Meyerhof-Parnas pathway (EMP), tricarboxylic acid (TCA) cycle, and cytochrome pathway (CCP), a relatively higher level of pentose phosphate pathway (PPP) and energy status.

The role of ROS-induced change of respiratory metabolism in pulp breakdown development of longan fruit during storage

Compared to the control longans, hydrogen peroxide (H2O2)-treated longans exhibited higher index of pulp breakdown, higher fruit respiration rate, higher activities of pulp phosphohexose isomerase (PGI), succinate dehydrogenase (SDH), cytochrome C oxidase (CCO), ascorbic acid oxidase (AAO) and polyphenol oxidase (PPO), but lower activity of pulp nicotinamide adenine dinucleotide kinase (NADK). H2O2-treated longans also exhibited lower total activities of pulp glucose-6-phosphate dehydrogenase (G-6-PDH) and 6-phosphogluconate dehydrogenase (6-PGDH), lower levels of pulp NADP(H), but higher levels of pulp NAD(H). These data indicated that H2O2-stimulated longan pulp breakdown was owing to a decreased proportion of pentose phosphate pathway (PPP), the increased proportions of Embden-Meyerhof-Parnas pathway (EMP), tricarboxylic acid (TCA) cycle and cytochrome pathway (CCP) in total respiratory pathways. These findings further revealed that H2O2 could enhance respiration rate, and thus accelerate pulp breakdown occurrence and shorten the shelf life of longan fruit.

Changes in respiration and structure of non-heading Chinese cabbage seeds during gradual artificial aging

Abstract The aging of seeds is a major problem in the agricultural sector. It is also a complex biological question that remains unclear for many crop seeds. In this experiment, we investigated how different ageing levels influence seeds germination, storage components, structure, respiration metabolism, and whether respiration is a promising indicator that can non-destructively evaluate seed aging. First, we obtained non-heading Chinese cabbage seeds with varying ageing levels by applying artificial aging treatments over a period of six days (0 d–6 d). Subsequently, respiration related indexes and ultrastructural observations were conducted. Our results showed that the respiratory rate remains low when seeds have a low water content. With the increased water content, the activities of respiratory-related enzymes, phosphohexose isomerase (PGI) and malate dehydrogenase (MDH), reached maximum levels when seeds were aged for two days. Respiration rates peaked one day later, followed by a rapid decline with increasing age. The ageing process consumed a large amount of storage components (e.g. soluble sugar, sucrose, and starch), leading to the degradation of mitochondria, proteasomes, fat bodies and cell nuclei in the aged seeds, which resulted in the reduction of respiratory rates. This, in turn, negatively affected seed germination. When seeds germinated (1 h–6 h, 1 d–6 d) under standard germination condition, the germination rate and respiratory rate showed significant correlation. Especially for 5 h and 6 h, the correlation coefficients reached 0.954 and 0.976 respectively. Measured at those times, respiratory rate should be a promising indicator for seed aging.

Respiratory pathway metabolism and energy metabolism associated with senescence in postharvest Broccoli (Brassica oleracea L. var. italica) florets in response to O2/CO2 controlled atmospheres

Broccoli is a highly perishable vegetable with abundant nutritional and medical value. Recent studies indicated that O2/CO2 controlled atmospheres (CA) was an effective method for broccoli storage.In this study, ATP (adenosine triphosphate) content, energy charge level, respiratory pathway and their key enzymes of broccoli (Brassica oleracea L. var. italica) were investigated, employed CA treatments of 70% O2+30% CO2, 60% O2+40% CO2, 50% O2+50% CO2, 40% O2+60% CO2, 30% O2+70% CO2 at 10°C. The 50% O2+50% CO2 treatment led to an obvious decrease in respiration rate of broccoli and it could inhibit the reduction of ATP level, energy charge level, SDH (succinic dehydrogenase), CCO (cytochrome oxidase), and boost the G-6-PDH (glucose-6-phosphate dehydrogenase)+6-PGDH (6-phosphogluconate dehydrogenas) activity. Treatment of 50% O2+50% CO2 suppressed reduction of the TCA (tricarboxyfic-acid-cycle) and CCP (cytochrome oxidase pathway) rate, and increased the HMP (phosphopentose pathway), while had little impact on the EMP (embden-meyerhof-parnas) rate and PGI (phosphohexose isomerase) activity. Compared to 50% O2+50% CO2 treatment, treatment of 30% O2+70% CO2 had an opposite effect on broccoli. Results indicated that O2/CO2 controlled atmospheres could alter the proportion of respiratory pathway, and 50% O2+ 50% CO2 treatment could enhance the endurance capability of broccoli to high CO2 concentration according to the changes of respiratory pathway and delay in its senescence though relatively higher ATP.

Effect of Photoperiod on Key Enzyme Activities of Respiration in Nectarine Buds During Dormancy Induction

Shuguang ( Prunus persica var. nectariana cv. Shuguang) nectarine was used to study effects of photoperiod on key-enzyme activities of respiration during dormancy induction. The dormancy status was determined with sprouting ability. Spectrophotometry was used to investigate activities of phosphohexose isomerase (PGI), malic dehydrogenase (MDH), and glucose-6-phosphate dehydrogenase (G6PDH). The results revealed that short day (SD) treatment promoted dormancy induction while long day (LD) treatment postponed the process. During dormancy induction, PGI activities declined, MDH activities changed little, and G6PDH activities increased both in flower buds and leaf buds. PGI activities and MDH activities in SD treatment were lower than control, and G6PDH activities were higher, which was opposite with LD treatment. The changes of respiratory key-enzyme activities were adjusted by photoperiod and correlated with the development of dormancy induction.

Role of Serum Enzymes in Assessing the Efficacy of Radiation Therapy for Human Carcinoma of Uterine Cervix.

In different stages of carcinoma of the uterine cervix, the activities of serum 5'-nucleotidase, lactate dehydrogenase (LDH), phosphohexose isomerase (PHI), γ-glutamyl transpeptidase (GGT), trans-aminases, and phosphatases were studied before and after radiation treatment. Glycolytic enzymes (LDH, PHI) were found to be increased from stage I onwards, whereas GGT, glutamate oxaloacetate trans-aminase, glutamate pyruvate transaminase, and acid and alkaline phosphatases increased only in the advanced stages (stages III, IV), when compared with normal values. 5'-Nucleotidase was found to be increased significantly from stage II onwards when compared with the normal. The increased levels of these enzymes were reversed to near normal levels after radiotherapy. The increased levels of serum transaminases, phosphatases, and GGT in the advanced stages of carcinoma of uterine cervix may be explained on the basis of liver involvement and bone metastasis. The degree of increase in the activities of PHI and LDH may reflect the status of the cancer. The activity of 5'-nucleotidase in serum may be used as an additional marker to assess the status of carcinoma of uterine cervix under circumstances when other markers fail to provide clear indications.

Comparative study of the effects of β-sitosterol, estradiol and progesterone on selected biochemical parameters of the uterus of ovariectomised rats

A comparative study was made of the effects of β-sitosterol, estradiol-17β and progesterone, individually and in combinations, on certain biochemical parameters important to carbohydrate metabolism in the uteri of adult ovariectomised rats. β-Sitosterol (SITO), estradiol (E 2) and combined treatment (SITO + E 2) induced significant increases in glycogen concentration and the activities of glucose-6-phosphate dehydrogenase (G6PDH), phosphohexose isomerase (PHI) and total lactate dehydrogenase (LDH). Pro- gesterone (P) administration however, raised only the uterine PHI and LDH activities. Co-administration of P with β-sitosterol (P + SITO) suppressed the SITO-induced increase in glycogen concentration and G6PDH activity. On the other hand, combined treatment (P + SITO) augmented total LDH activity.

Tumor Enzymes and Prognosis in Transitional Cell Carcinoma of the Bladder: Prediction of Risk of Progression in Patients with Superficial Disease

The activities of 6 enzymes of carbohydrate metabolism were estimated in superficial transitional cell carcinomas from 103 patients undergoing transurethral resection of the bladder for the first time. The patients were followed by quarterly endoscopic examinations for a maximum of 81 months (median 33 months). During followup 24 patients had progressive disease. The activities of phosphofructokinase and phosphohexose isomerase were significantly lower in tumors from patients whose disease had superficially invaded the lamina propia (stage pT1) than in others in whom it was confined to the bladder mucosa (stage pTa). Similarly the activities of the 2 enzymes were significantly higher in well differentiated (grade 1) than in moderately well differentiated (grade 2) carcinomas. Univariate analyses using the log rank test showed that neither pathological stage nor malignancy grade of the carcinoma was a significant factor in predicting the risk of progression. Of the 6 enzymes, below median activities of phosphofructokinase, lactate dehydrogenase and phosphohexose isomerase were associated with a significantly increased risk of progression in these patients. Multivariate analyses using Cox’s proportional hazards model showed that the activity of lactic dehydrogenase in superficial transitional cell carcinoma is an independent prognostic factor in predicting the risk of progression. It is postulated that the measurements of the activities of the 3 enzymes in tumors from patients with superficial transitional cell carcinoma might help to select individual patients with a high risk of progression for adjuvant intravesical treatments.

Zur diagnostischen Wertigkeit der Sialochemie

In 196 patients suffering from disease of the cephalic salivary glands and in 57 healthy controls the concentration of albumin in parotid and submandibular saliva was measured by the immunodiffusion technique. To summarize the results, albumin seems to be a reliable marker of inflammations of the salivary glands even in the early stages and is therefore recommended for the primary diagnostic and the follow-up of acute and chronic inflammatory conditions of the major cephalic salivary glands. In combination with the evaluation of the flow rate, other sialochemic parameters like phosphohexose isomerase and kallikrein activity, B-mode sonography and fine needle aspiration biopsy the frequency of x-ray examination of the radiosensitive salivary glands may be reduced.

Serum Phosphohexose Isomerase Activities in Patients with Colorectal Cancer

Pretreatment levels of phosphohexose isomerase (PHI) were above the cutoff limit of 107 IU/l in 41% of patients with benign intestinal diseases and in 46% of patients with colorectal cancer. Sensitivity of PHI was related to the presence of distant metastasis and the location of the primary tumor. Patients with rectal tumors presented a lower sensitivity than patients with colonic tumors. Pretreatment levels of PHI had prognostic value and patients with elevated levels of this enzyme showed a shorter disease-free interval in comparison with those patients with normal PHI activities. However, the prognostic significance of PHI was not independent of Dukes' classification. The present study indicates that PHI is not useful in the follow-up of patients with colorectal cancer after curative surgery because of its low sensitivity in the diagnosis of recurrences (47%) and its low specificity in patients without evidence of disease (76%).

The Diagnostic Validity of the Serum Tumor Marker Phosphohexose Isomerase (PHI) in Patients with Gastrointestinal, Kidney, and Breast Cancer

The diagnostic validity of the glycolytic enzyme phosphohexose isomerase (PHI) as a serum tumor marker was evaluated. For this purpose the sensitivity of PHI was determined in 435 patients with histopathologically defined, malignant gastrointestinal, kidney, and mammary tumors prior to primary treatment. To assess the specificity, PHI serum activities were measured in 181 patients with benign diseases and disorders from an internal practice. In gastrointestinal and kidney cancer, PHI reached an overall diagnostic sensitivity of about 70%, and a specificity of 92% was obtained. Even in early stages without metastasis, elevated PHI serum levels were found in about 60% of the patients. In mammary cancer, however, a sensitivity of only 40% was observed. PHI activity can be measured without the need for highly technical skills and equipment, in a short time and at low cost. These data suggest that serum PHI can be a useful indicator in the preventive checkup of gastrointestinal and renal cancer in medical practice.

Enzyme Studies in Human Transitional Cell Carcinoma of the Urinary Bladder

The activities of six enzymes of carbohydrate metabolism were estimated in tissue samples from 99 patients with transitional cell carcinoma of the urinary bladder undergoing transurethral resection. The results were analysed according to the stage of the disease and the malignancy grade of the carcinoma. There were statistically significant differences in the activities of three enzymes between various stages and grades. The activities of phosphofructokinase (PFK), α-glycerolphosphate dehydrogenase (α-GPDH), and phosphohexose isomerase (PHI) showed significant decreases with increased stage and grade. Of the total of 64 patients with superficial disease at presentation, five developed progressive disease during the course of this investigation. The activities of the three enzymes in these patients were compared to the median values for the group of patients with superficial disease. The activity of PFK was observed to be below the median value in all the five patients whereas the activities of α-GPDH and PHI showed similar patterns in four of the five patients. These preliminary data indicate that, in association with established clinical parameters, the measurement of the activity of these three enzymes may prove useful in selecting patients with an increased potential for developing progressive disease.

Phosphohexose isomerase in hypernephroma. Significance as serum tumor marker, comparison to other glycolytic enzymes and isozyme patterns in normal and tumor tissue.

In hypernephroma an overall diagnostic sensitivity of 72% and a specificity of 87% was found for the serum tumor marker phosphohexose isomerase (PHI). Both in early stage disease and in well differentiated tumors a sensitivity of about 60% was reached. In contrast the sensitivity of three other glycolytic enzymes tested was found to be less than 20%. Since the cancer induced elevation of PHI activity in the tumor was found to be comparable to those of the other test enzymes, elevated PHI serum activities cannot be attributed to overproportional PHI synthesis and unspecific cell-lysis. In 6 of 10 cases studied differences in the PHI isozyme pattern between the tumor and the normal tissue were found suggesting the occurrence of cancer associated structural alterations of PHI.

Activities of Phosphohexose Isomerase and Other Glycolytic Enzymes in Normal and Tumor Tissue of Patients with Neoplastic Diseases: Comparison with Serum Activities and Correlation to Tumor Staging and Grading

Of five glycolytic enzymes tested, only the serum activity of phosphohexose isomerase (PHI) was elevated in the vast majority of 140 patients with gastrointestinal, kidney or mammary carcinomas. However, in the tumor tissues all enzymes were increased to about the same extent. Thus, the measured increase in the serum activity of PHI is not due to a specific overproduction in the malignant cells. A general rise in the glycolytic enzyme activities in the malignant tissue could be detected already in early stages without metastases and in well-differentiated tumors.

Clinical significance and source of raised catalytic activities of phosphohexose isomerase in the CSF in meningitis.

The value of phosphohexose isomerase (EC 5.3.1.9) determination in the CSF in the diagnosis of meningitis was tested under routine conditions. In 48 patients with untreated bacterial meningitis, enzyme activity concentrations between 40 and 2335 U/l were measured, whereas the highest phosphohexose isomerase activity concentration in 92 patients with viral meningitis was 34 U/l. Lysis of the CSF leukocytes with Triton X-100 resulted in a substantial increase of phosphohexose isomerase activity. In bacterial meningitis these values increased to 200 to 7000 U/l, but remained under 150 U/l in viral meningitis. The raised enzyme activities are derived from the leukocytes and appear to reflect their functional and metabolic state. The information provided by the leukocyte morphology can thus be appreciably extended by phosphohexose isomerase determination.

Serum phosphohexose isomerase levels in patients with head and neck cancer.

Serum phosphohexose isomerase (PHI) levels were estimated in 28 patients with head and neck cancer. The mean value was significantly higher when compared to the controls. There was no difference in mean PHI value with respect to the character of the lesion or with the histopathological type of growth. The activity was increased with the advancement of the stage of cancer. With radiotherapy, a gradual and significant decrease in serum PHI activity was observed.