Alfalfa Proteins: Isolation and Partial Characterization of the Major Component — Fraction I Protein |
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| Authors: | L L HOOD S G CHENG U KOCH J R BRUNNER |
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| Affiliation: | Authors Cheng, Koch, and Brunner are affiliated with the Dept. of Food Science &Human Nutrition, Michigan State Univ., East Lansing, Ml 48824;Author Hood, formerly affiliated with the Dept. of Food Science &Human Nutrition is now with Devro, Inc., Box 858, Sommerville, NJ 08876. |
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| Abstract: | Fraction I protein was extracted from fresh alfalfa (Medicago sativa) leaves and purified by ammonium sulfate fractionation, DEAE-cellulose and Sephadex G-200 chromatography. The isolate possessed a specific activity for ribulosebisphosphate carboxylase EC 4.1.1.39) of 1.01 units/mg protein. An approximate molecular weight of 573,000 was determined from values of So20,w (18.7) and Do20,w (2.97). The protein contained 26 disulfide and 37 sulfhydryl groups—only one of which was titratable in the undenatured protein complex. It migrated as a single boundry by Tiselius electrophoresis and as a dense zone in polyacrylamide gels (disc). In the presence of SDS, two principal subunits of ～52,000 and ～12,500 daltons were revealed. Based on the FAO/WHO (1973) provisional pattern for essential amino acids, the protein was slightly deficient in sulfur-containing residues. |
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