Date of Award:

1972

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Nutrition, Dietetics, and Food Sciences

Department name when degree awarded

Nutrition and Food Sciences

Advisor/Chair:

Gary H. Richardson

Abstract

An assay for catheptic activity of lamb gastric tissue extract has been proposed which involves the use of a pH 3.5 hemoglobin substrate following activation of zymogens at pH 2.0, 25C for 30 min.; and inactivation at pH 8.0, 40C for 30 min thereby eliminating the effects of pepsin and rennin. Cathepsin was isolated and purified by ammonium sulfate fractionation, acetone precipitation and gel viii filtration. The purified cathepsin represented approximately 50 fold increase in specific activity over the original extract and a recovery of 15% of the original activity. Degree of purity was monitored by isoelectric focusing in polyacrylamide gels. Some characteristics of the cathepsin were determined. The purified cathepsin hydrolyzed urea-denatured hemoglobin readily at pH 3.5, but it had no activity on substrates specific for cathepsins A, B or c. a-N-benzoyloxycarbonyl- L-gutamyl-L-tyrosine, a-N-benzoyl-L-argininamide hydrochloride and a-N-acetyl-L-tyrosinamide. Approximate isoelectric point was pH 5.6. The purified enzyme was similar to cathepsin D. Parmesan, Romano, and Cheddar cheese manufactured with lamb pregastric esterase and gastric extracts added to the curd or milk were superior in flavor when both were employed, and either extract alone made better cheese than the uninoculated control.

Checksum

d9039ac71a53f26d6ae98ce3b8e08e47

Included in

Nutrition Commons

Share

COinS