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Title: ISOLATION AND CHARACTERIZATION OF BEEF PROTEINS THAT ENHANCE NONHEME IRON BIOAVAILABILITY (POSTER PRESENTATION FOR EXPERIMENTAL BIOLOGY 2000 MTG., APRIL 2000)

Author
item SWAIN, JAMES - IA STATE UNIV., AMES, IA
item Tabatabai, Louisa
item REDDY, MANJU - IA STATE UNIV., AMES, IA

Submitted to: Federation of American Societies for Experimental Biology Conference
Publication Type: Abstract Only
Publication Acceptance Date: 3/15/2000
Publication Date: 6/20/2000
Citation: N/A

Interpretive Summary:

Technical Abstract: The objective of the study was to isolate and characterize beef muscle proteins that enhance nonheme iron bioavailability. Beef top sirloin was cooked, lyophilized, and reconstituted with water prior to in vitro enzymatic digestion. Following centrifugation, the supernatant was subjected to sequential ultrafiltration using 10 Kd and1 Kd molecular weight cut-off membranes. Iron bioavailability was assessed by Caco-2 cel monolayer Fe uptake using an extrinsic labeling method. Cell iron uptake was 46% higher with the 1K retentate (1KR) as compared to the 10K retentate and 1K filtrate and 5-fold greater than iron-nitrilotriacetic acid (Fe- NTA). Therefore, the 1KR was chosen for further analysis. Immobilized metal affinity chromatography (IMAC) of the 1KR yielded a series of four peaks: three distinct peaks (P1, P3, P4) and one with a few closely associated peaks (P2). Peaks 1-4 conferred higher iron solubility than FeCl3 alone, 2.1, 3.6, 4.7 and 4.4-fold, respectively, at pH 6. Similarly when compared to Fe-NTA, P1-4 were found to enhance Fe uptake by 3 to 5- fold (p<0.01). Gel electrophoresis (SDS-PAGE) illustrated that P1-4 each contained many peptides ranging from 1-5 Kd. Matrix assisted laser desorption ionization-time of flight (MALDI-TOF) analysis confirmed these findings. Amino acid composition analysis revealed that peptides in P1-4 contained a high proportion of histidine. Our results suggest that the enhancing effect of beef on nonheme iron absorption may be due to low- molecular weight peptides produced during gastrointestinal digestion.