Isolation and partial purification of the major storage protein from sweet potato (Ipomea batatas) with bioactive peptides exhibiting angiotensin converting enzyme inhibitory activity

Date

4-2009

Degree

Bachelor of Science in Agricultural Chemistry

College

College of Arts and Sciences (CAS)

Adviser/Committee Chair

Mary Ann O Torio

Co-adviser

Roberta N. Garcia

Committee Member

Mark Rickard N. Angelia

Abstract

The total soluble proteins from peeled sweet potato tuber were extracted using 50 mM potassium phosphate buffer, pH 7.5 with 0.5 M sucrose, 10 mM MgCl2, and 1% (w/v) ascorbic acid. The SDS-PAGE profile of crude extract reveals a 25 kDa major band known as sporamin. The major protein was purified by gel filtration chromatography on Sephadex G-25, ammonium sulfate fractionation, and dialysis against 50 mM potassium phosphate buffer (pH 7.5) containing 12.5% (v/v glycerol) and 0.1% (w/v) ascorbic acid. The protein content of the crude extract and the dialysate were found to be 0.752 mg/mL and 0.415 mg/mL, respectively. Protein enzymatic hydrolysates from the major soluble proteins were prepared using pepsin and thermolysin on different time intervals ranging from 3 minutes to 24 hours. Pepsin did not completely hydrolyze the globular proteins even after 24 hour digestion. On the other hand, thermolysin completely digested the globulins of sweet potato. Both pepsin and thermolysin hydrolysates of 1 hour and 24 hour digestion were assayed for its Angiotensin converting enzyme (ACE) inhibitory activity. The one-hour peptic hydrolysate did not exhibit inhibitory activity while the 24-hour peptic hydrolysate has 2.229 x 10-3 units ACE inhibitory activity. The one-hour and 24-hour thermolysin hydrolysates have 3.186 x 10' and 3332 x 10-3 units ACE inhibitory activity, respectively. The thermolysin hydrolysates are more potent ACE inhibitors as compared with pepsin hydrolysates.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993.5 2009 A13 M35

Document Type

Thesis

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