Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.21.4 (trypsin)
 42,187 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A previous study has characterized the major 47 kDa anti-sticking factor (ASF-I) from goat cauda-epididymal plasma (Roy, N., and Majumder, G.C., Biochim. Biophys. Acta, 991:114-122, 1989). This study reports the purification and characterization of ASF-II, another anti-sticking factor from the goat epididymal plasma. ASF-II was purified to apparent homogeneity by using concanavalin A-agarose affinity chromatography, DEAE-cellulose chromatography, alumina gel adsorption, and isoelectric focussing techniques. It showed a single protein band by both non-denaturing and SDS-polyacrylamide gel electrophoresis. ASF-II showed a molecular weight of 36,000 and a sedimentation constant of 2.4S. ASF-II is largely stable to heat treatment and it is a specific glycoprotein having high affinity and specificity for its anti-sticking action. At saturating concentration (1 nM) it inhibited adhesion of nearly 50% of spermatozoa to the glass surface of the haemocytometer counting chamber. Both the protein and sugar parts of the factor are essential for the anti-sticking activity since it lost its activity completely when treated with trypsin, L-fucosidase, or mannosidase. ASF-II does not coat the glass surface and it binds to spermatozoa. Data are consistent with the view that ASF-II has not been derived from the larger ASF-I molecule due to its enzymic modifications. Both ASF-I and -II had no effect on sperm forward motility as evidenced by spectrophotometric motility assays, indicating thereby the suitability of the factors to improve the existing sperm motility assays by eliminating the possibility of cell-sticking artifacts.
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PMID:Characterization of anti-sticking factor-II from goat epididymal plasma. 209 69

An anti-sticking factor (ASF-I) that showed high affinity for inhibiting adhesion of spermatozoa to glass was isolated from goat epididymal plasma and characterized. The factor was purified approx. 5600-fold and showed a single protein band when examined by non-denaturation and SDS-polyacrylamide gel electrophoresis. The molecular mass and S20w value of ASF-I were approx. 47 kDa and 4.25 S. ASF-I at a concentration of 1 nM showed nearly maximal anti-sticking activity when approx. 60% of the intact spermatozoa were prevented from adhesion to glass and it showed a high degree of protein specificity. Studies with trypsin and glycosidases demonstrated that both the sugar and protein parts of the molecule are essential for its anti-sticking activity. Evidence has been presented to support the view that the outer surface of sperm possesses specific ASF-I receptors that bind to 125I-labelled ASF and mediate cell adhesion to glass. ASF-I also showed high affinity for inhibiting agglutination of corpus-epididymal spermatozoa. The ASF activity was found to be distributed in all the tissues tested and its specific activity was markedly higher in blood plasma than in the tissues. The results suggest that ASF may play an important biological role by serving as a specific inhibitor of cell-substratum and cell-cell adhesions.
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PMID:Purification and characterization of an anti-sticking factor from goat epididymal plasma that inhibits sperm--glass and sperm--sperm adhesions. 271 14

The African swine fever (ASF) virus polyprotein pp220 is processed at Gly-Gly-X sites by a virally encoded SUMO-like protease to produce matrix proteins p150, p37, p34, and p14. Four Gly-Gly-X sites are used to produce the matrix proteins, but the polyprotein contains an additional 15 sites potentially recognized by the protease. This study shows that cleavage occurs at many, if not all, Gly-Gly-X sites, and at steady state, p150 and p34 are minor products of processing. Significantly, only the final structural proteins, p150 and p34, were found in mature virions, suggesting that there is a mechanism for excluding incorrectly processed forms. ASF virus is assembled on the cytoplasmic face of the endoplasmic reticulum, and the distribution of pp220 products between membranes and cytosol was studied. Incorrectly processed forms of p34 were recovered from both the cytosol and membrane fractions. Interestingly, p34 was only detected in the membrane fraction, and of the many processed forms bound to membranes, only p34 was protected from trypsin, suggesting envelopment. The majority of the incorrectly processed forms of p150 were recovered from the cytosol. Again, the correct product of processing, p150, was selectively recruited to membranes. Sucrose density centrifugation showed that membrane-associated forms of p34 and p150 assembled into large structures suggestive of a viral matrix, while cytosolic and/or incorrectly processed forms of pp220 did not. Taken together, these results suggest that association with cellular membranes is important for regulating the correct processing of pp220 and the packaging of matrix proteins into virions.
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PMID:Membrane association facilitates the correct processing of pp220 during production of the major matrix proteins of African swine fever virus. 1252 2