Glycolytic Cycle Enzymes Research Articles

The Enolase of Borrelia burgdorferi Is a Plasminogen Receptor Released in Outer Membrane Vesicles

The agent of Lyme disease, Borrelia burgdorferi, has a number of outer membrane proteins that are differentially regulated during its life cycle. In addition to their physiological functions in the organism, these proteins also likely serve different functions in invasiveness and immune evasion. In borreliae, as well as in other bacteria, a number of membrane proteins have been implicated in binding plasminogen. The activation and transformation of plasminogen into its proteolytically active form, plasmin, enhances the ability of the bacteria to disseminate in the host. Outer membrane vesicles of B. burgdorferi contain enolase, a glycolytic-cycle enzyme that catalyzes 2-phosphoglycerate to form phosphoenolpyruvate, which is also a known plasminogen receptor in Gram-positive bacteria. The enolase was cloned, expressed, purified, and used to generate rabbit antienolase serum. The enolase binds plasminogen in a lysine-dependent manner but not through ionic interactions. Although it is present in the outer membrane, microscopy and proteinase K treatment showed that enolase does not appear to be exposed on the surface. However, enolase in the outer membrane vesicles is accessible to proteolytic degradation by proteinase K. Samples from experimentally and tick-infected mice and rabbits as well as from Lyme disease patients exhibit recognition of enolase in serologic assays. Thus, this immunogenic plasminogen receptor released in outer membrane vesicles could be responsible for external proteolysis in the pericellular environment and have roles in nutrition and in enhancing dissemination.

English

During spermatogenesis the X-chromosome is inactivated, but several glycolytic cycle enzymes have been found to have spermatogenic cell specific isoforms encoded by the X-chromosome counterpart genes located on the autosomes. Here, the promoters of the human glycerol kinase gene family were cloned: the somatic gene called GK-Xp, and the two testis-specific isoforms called GK-1 and GK-2, using Alu-GSP primers. The structure and function of the promoters were determined by sequencing and in situ expression studies using GFP as reporter. The transcription initiation sites were mapped by RACE and, these were found at -112 for GK-Xp, -46 for GK-1, and for GK-2 at -57 nucleotide positions, upstream of the translation start codon. The GK-Xp promoter specifically contains a TATA-like motif at -26, and a CCAAT motif at -149, which are not found in either the GK-1 or GK-2 promoters. Interestingly, GK-1 contains an Inr motif, a Sp1 binding site at -11, and a DPE motif at +27 positions, whereas GK-2contains an Inr motif, a CRE at -11, a DPE at +29 and a RARE motif at +43 positions. In addition, they both contain MEP-2 and Ets motifs, in common with other testis-specific metabolic enzymes genes, such as PGK-2 and PDHA-2. Key words: Spermatogenesis, transcription, gene expression.

Circadian variations of phosphohexose-isomerase (PGI) in multiple myeloma

One of the problems common to all research on the neoplastic cell is that of establishing whether the differences that exist between normal and neoplastic activity are in direct relation to the transforming phenomenon or if they represent, instead, secondary or overlapping phenomena. Warburg, in 1924, first produced evidence of a higher rate of aerobic glycolysis in neoplastic tissue than in normal tissue, which is correlated with the disdifferentiation and growth rate of the tumour. Our research concerned the study of phosphohexose-isomerase (PGI) a glycolytic cycle enzyme (properties) from a chronobiological point of view in a group of 11 “healthy” subjects and in a group of 11 patients with multiple myeloma. The data obtained were analyzed using the “group mean cosinor” method; the rhythm parameters (mesor, amplitude, acrophase) were compared using adequate statistical methods. The elaborated data show a significant circadian rhythm in both the “healthy” subjects and in the patients affected by myeloma; in particular, we noted a significant difference between the “mesors” and the “amplitudes” of the two groups expressed in per cent. Moreover, these results exclude any possible effect of sex and age upon PGI activity in the serum.

Histochemical localization of glycogen and some representative enzymes of glycolytic cycle in the cheliped muscle of Scylla serrata (Forskål) (Brachyura: Decapoda)

Glycogen, phosphorylase, aldolase, a-glycerophosphate dehydrogenase, lactic dehydrogenase and glucose-6-phosphate dehydrogenase were localized histochemically in the cheliped muscle of Scylla serrata (Forskal) in normal, destalked, destalked receiving eyestalk extract injection and intact injected with eyestalk extract.

Enzymes of glycolytic cycle in periodontal tissues of the guinea pig

The enzymes of the glycolytic cycle: phosphohexoisomerase, aldolase, phosphoglycerokinase and glucose-6-phosphatase were determined in the gingiva, periosteum and periodontium of the mandibular incisor region in the guinea pig and compared with their activities in the liver, kidneys, adrenals, pituitary and testes of the same animal. The enzymatic activities of the periodontal tissues were generally high. The phosphohexoisomerase and the aldolase activity in periosteum and periodontium was as high as in the other tissues. The phosphoglycerokinase activity of periosteum and gingiva were higher than in the other tissues. The glucose-6-phosphatase activity in periosteum and periodontium was about half as high as the liver activity.