Purification and characterization of an acidic trypsin/subtilisin inhibitor from tortoise egg white |
| |
Authors: | AK Ray MK Guha NK Sinha |
| |
Institution: | Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Calcutta 700 099 India |
| |
Abstract: | Egg whites of three species of tortoise and turtle have been compared by gel chromatography for inhibitory activity against proteases. The egg white of Geomda trijuga trijuga Schariggar contains trypsin/subtilisin inhibitor while the egg white of Caretta caretta Linn. contains both trypsin and chymotrypsin inhibitors. No protease inhibitory activity has been detected in the egg white of Trionyx gangeticus Cuvier. An acidic trypsin/subtilisin inhibitor has been purified to homogeneity from the egg white of tortoise (G. trijuga trijuga). It is a single polypeptide chain of 100 amino acid residues, having a molecular weight of 11 700. It contains six disulphide bonds and is devoid of methionine and carbohydrate moiety. Its isoelectric point is at pH 5.95 and is stable at 100°C for 4 h at neutral pH. The inhibitor inhibits both trypsin and subtilisin by forming enzyme-inhibitor complexes at a molar ratio close to unity. Their dissociation contants are 7.2·10?9 M for bovine trypsin adn 5.5·10?7 M for subtilisin. Chemical modification of amino groups with trinitrobenzene sulfonate has reduced its inhibitory activities against both trypsin and subtilisin, but the loss of its trypsin inhibitory activity is faster than of its subtilisin inhibitory activity. It has independent binding sites for inhibition of trypsin and subtilisin. |
| |
Keywords: | Protease inhibitor Trypsin Subtilisin (Reptile egg white) TAME ATEE TNBS 2 4 6-trinitrobenzene sulfonate BPN′ To whom correspondence should be addressed |
本文献已被 ScienceDirect 等数据库收录! |