Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P56851 (epididymal)
 11,273 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Aspartate carbamyltransferase (ACTase) of the testis, epididymis, and prostate gland was determined throughout the lifetime of rats. Testicular ACTase concentration (nmoles carbamyl aspartate formed per microgram protein) peaked at about 45 g body weight, then declined. Epididymal concentration increased up to 100 g body weight and around 155 g plateaued in the caput and declined slightly in the cauda. A lifetime decline followed the maximal prostatic concentration found in the youngest test rats. Maximal total testicular activity, which occurred at 350 g, was undiminished in the oldest rats, while maximal epididymal activity occurred in the latter group. Total prostatic activity peaked at about 450 g body weight. Castration and testosterone replacement showed prostatic ACTase levels to be hormone dependent.
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PMID:Lifetime changes in aspartate carbamyltransferase of reproductive tissue of male rats. 44 23

Aspartate transcarbamoylase from wheat germ is irreversibly inactivated by the triazinyl dye Procion Red HE3B. Since triazinyl dyes may mimic nucleotides, and UMP is a known allosteric modifier of this enzyme, the reaction was studied to elucidate whether the dye is an 'affinity label' for the enzyme. The reaction is apparently first order in the first 5-10 min, but is more complex in the longer term and does not go to completion. Kinetic analysis of the initial phase suggests that there are two parallel reactions, one saturable (dye binds reversibly before reaction) and one non-saturable (biomolecular). The apparent rate constant kapp (i.e. the sum of the rate constants for the parallel reactions) varies only slightly over the pH range 7-10. In the presence of a number of active centre ligands, as well as the allosteric ligand UMP, there is a clear increase in kapp. This finding is contrary to the reduction in rate of inactivation (protection) normally provided by ligands against active-site directed reagents, suggesting that in the saturable reaction, there is a conformational change upon dye-binding that increases the exposure of the essential residue(s) with which the dye reacts. These results show that, although it probably inactivates by reaction with specific amino-acid residues, the dye is not bound at the substrate-binding or allosteric sites, i.e. it is not an affinity-labeling reagent in the usual sense.
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PMID:Inactivation of wheat-germ aspartate transcarbamoylase by the triazinyl dye, procion red HE3B. 173 53

A biologically active, low-molecular-weight, chromium-binding substance present in milk (M-LMCr) was isolated from bovine colostrum and purified more than 2000 times by means of ethanol precipitation and successive ion-exchange and Sephadex gel chromatographies. The purified M-LMCr appeared to be an anionic organic Cr compound with a molecular weight of 1500, as determined by gel permeation chromatography. It contained aspartic acid, glutamic acid, glycine and cysteine in a ratio of 5:4:2:1 and no detectable carbohydrate. Although we were unable to detect nicotinic acid, some ultraviolet-absorbing (lambda max 260 nm) chemical structure was shown to be a constituent. Purified M-LMCr stimulated the rates of both [U-14C]glucose oxidation and [3-3H]glucose conversion into lipid in rat epididymal adipocytes at Cr concentrations greater than 1.5 ng/mL in relation to insulin action. This substance appears to have properties similar to those of glucose tolerance factor in yeast and the low-molecular-weight, chromium-binding substance present in mammalian liver. The role of M-LMCr in Cr nutrition and detoxication is discussed.
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PMID:Purification and properties of biologically active chromium complex from bovine colostrum. 327 60

A low-molecular-mass chromium-binding substance (LMCr), which is recognized as a detoxification ligand of chromium, was isolated from the livers of rabbits injected intravenously with K2Cr2O7 (200 mumol Cr/kg body wt) as a biologically active form. LMCr appears as an anionic, organic Cr compound with a relative molecular mass of 1500. It is composed of glutamic acid or glutamine, glycine, cysteine and aspartic acid or asparagine with a Cr/amino-terminal residue ratio of 4:1. The purified LMCr (10-300 ng Cr/ml) shows in vitro activities comparable to those of glucose tolerance factor in relation to insulin action. In the presence of insulin it enhances [U-14C]glucose conversion to 14CO (23-30% up) in rat epididymal adipocytes above the value obtained with insulin alone. LMCr also stimulates the rate of [3-3H]glucose incorporation into lipid by 30-40% with insulin or by 15-23% without insulin, as compared with the basic value obtained with insulin alone or without insulin. These findings suggest that LMCr plays essential roles in both glucose metabolism and detoxification of invaded Cr in the body.
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PMID:Isolation of a biologically active low-molecular-mass chromium compound from rabbit liver. 359 4

Using mechanical and chemical dissection methods, fibrous sheath was isolated both from normal ejaculated human spermatozoa and from rabbit cauda epididymal spermatozoa. The same techniques did not produce a pure preparation of fibrous sheath from ejaculated rabbit spermatozoa, suggesting that further cross-linking and stabilization of sperm structures occurs in response to components of the seminal plasma. The isolation procedures were monitored by phase contrast microscopy and the purity of the fibrous sheath was verified by electron microscopy. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of isolated human fibrous sheath revealed at least 14 protein bands of which the most intensely stained were of molecular weight 84, 72, 66.2, 57, 32 and 28.5 kDa. The rabbit fibrous sheath revealed at least 10 protein bands, of which the most intensely stained were 35.2, 32.7 and 28.5 kDa. The amino acid composition of the purified fibrous sheath from human and rabbit spermatozoa was similar, being high in aspartic acid and/or asparagine and glutamic acid and/or glutamine, serine, alanine, leucine, lysine and glycine, but low in histidine, tyrosine and isoleucine. This composition is similar to that reported for the rat and suggests that mammalian sperm tail fibrous sheaths are composed of similar types of proteins, although there are apparent differences in protein components between species.
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PMID:Isolation and characterization of human and rabbit sperm tail fibrous sheath. 923 58

The D-isomer of aspartic acid (D-Asp) has been found in rat testes. In the present study, samples of testicular venous blood plasma, rete testis fluid, interstitial extracellular fluid, luminal fluid from the seminiferous tubules, testicular parenchymal cells, epididymal spermatozoa and peripheral blood plasma were collected and analyzed for D-Asp by two methods, an enzymatic and a chromatographic HPLC method. The two methods gave very similar results for all samples. The highest concentrations of D-Asp (about 120 nmol/ml) were found in testicular venous blood plasma, with slightly lower concentrations in rete testis fluid (95 nmol/ml) and epididymal spermatozoa (80 nmol/g wet weight). Lower levels were found in testicular parenchymal cells (which would comprise mostly spermatids and spermatocytes), luminal fluid from the seminiferous tubules and interstitial extracellular fluid (26, 23 and 11 nmol/ml respectively). However, these values were all higher than those for peripheral blood plasma (6 nmol/ml). It would appear that D-Asp is being secreted by the testis mostly into the venous blood, passing thence into the rete testis fluid and being incorporated into the spermatozoa at the time or after they leave the testis. The distribution of D-Asp is thus quite different from that of testosterone, and its role and the reason for its high concentration in the male reproductive tract remain to be elucidated.
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PMID:Secretion of D-aspartic acid by the rat testis and its role in endocrinology of the testis and spermatogenesis. 977 87