HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Church, F. C. Articles by Swaisgood, H. E. Search for Related Content PubMed Articles by Church, F. C. Articles by Swaisgood, H. E.

Hydrolysis of Milk Proteins by Immobilized Streptomyces griseus Pronase¹

Department of Food Science, North Carolina State University, Raleigh 27650

ABSTRACT

Streptomyces griseus pronase was coupled covalently to porous succinamidopropyl-glass beads with 1-ethyl-3-dimethylaminopropyl carbodiimide. The milk proteins, -lactalbumin, ribonuclease A, bovine serum albumin, ß-lactoglobulin, whole casein, commercial casein, _s1-casein, ß-casein, and -casein were recirculated through a packed-bed column of immobilized pronase. The rate and extent of hydrolysis of the milk proteins were estimated by a 2,4,6-trinitrobenzenesulfonic acid assay which measured liberated -amino groups. Rates of hydrolysis varied from .46 µmol -amino groups released min^–1 100 mg glass beads^–1for ribonuclease A to 7.70 µmol -amino groups released min^–1100 mg glass beads^–1 for a commercial preparation of casein while the extent of hydrolysis ranged from 5% -amino groups released in 30 min for ribonuclease A to 44% -amino groups for _s1-casein in 15 min. Sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis visualized the rapid loss of major casein bands and degradation of the generated peptide fragments. Pseudo-first order rate constant for N, N-dimethyl casein prepared by reductive alkylation was 5 x 10^–2 min^–1, while for casein, 7 x 10^-2 min^–1 Inclusion of 4 M urea with bovine serum albumin and stimultaneous exposure to immobilized pronase gave a twofold increase in rate and extent of hydrolysis.

¹ This material is based upon work supported by the US Department of Agriculture under Agreement No. USDA/SEA 5901-0410-9-0287-0. This is paper 6587 of the Journal Series of the North Carolina Agricultural Research Service. The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of the products.