Unusual properties of crocodilian ovomacroglobulin shown in its methylamine treatment and sulfhydryl titration
The inhibitory activity of chicken and crocodilian ovomacroglobulins against trypsin was measured before and after their incubation with methylamine. The result for crocodilian ovomacroglobulin showed that methylamine treatment destroyed half of its activity, in unique contrast to human alpha 2-macroglobulin and chicken ovomacroglobulin for which methylamine either destroys the inhibitory activity of the former completely or does not affect that of the latter at all. Free sulfhydryl groups of chicken and crocodilian ovomacroglobulins were titrated with 5,5'-dithiobis(2-nitrobenzoic acid) before and after incubation with trypsin. Prior to the incubation with trypsin the chicken and crocodilian proteins respectively had 0 and 1 titratable sulfhydryl per molecule of Mr 720,000. After treatment with trypsin the crocodilian protein had 3.5-4 titratable sulfhydryls, whereas there were no titratable sulfhydryls in the chicken protein. After denaturation of the crocodilian protein in sodium dodecyl sulfate at 100 degrees C the number of titratable sulfhydryls was 4. Chicken ovomacroglobulin again did not have an appreciable number of titratable sulfhydryls under similar denaturing conditions. Incubation of crocodilian protein with (14C)methylamine showed an incorporation of at least 2 mol of methylamine per molecule. The result indicated the presence of three intramolecular thiol ester bonds in crocodilian ovomacroglobulin with differential stability against external perturbations.
- Research Organization:
- Univ. of Tokyo, Japan
- OSTI ID:
- 5858992
- Journal Information:
- Arch. Biochem. Biophys.; (United States), Vol. 2
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
AMINES
BIOLOGICAL EFFECTS
GLOBULINS
INACTIVATION
CHICKENS
REPTILES
SULFHYDRYL RADICALS
TRYPSIN
ANIMALS
BIRDS
ENZYMES
FOWL
HYDROLASES
ORGANIC COMPOUNDS
PEPTIDE HYDROLASES
PROTEINS
RADICALS
SERINE PROTEINASES
VERTEBRATES
560301* - Chemicals Metabolism & Toxicology- Cells- (-1987)