Starch Gel Electrophoresis of Products of Action of Crystalline Rennin on Casein and Its Components
1968; Elsevier BV; Volume: 51; Issue: 7 Linguagem: Inglês
10.3168/jds.s0022-0302(68)87115-2
ISSN1529-9066
Autores Tópico(s)Protein Hydrolysis and Bioactive Peptides
ResumoThe primary and secondary phases of rennin action on whole casein and Kcasein were investigated by high resolution starch gel electrophoresis.K-Casein was the only component of whole casein attacked during 50 rain of enzyme action, resulting in one major and two minor components with faster mobilities than whole a~-casein and two minor components with slower mobilities than K-casein.Thirty and six-tenths per cent and 48.4% of the K-casein were solubilized at pH 4.60 after 60 and 120 rain of rennin action at pH 6.80 and 36 C. The balance of the ~casein aggregated.The para-K-caseins resulting from 60 and 130 rain of rennin action showed an electrophoretic composition similar to that reported by others (3, 10).The 12% trichloroacetic acid insoluble product recovered from ~-casein after 30 rain of rennin action showed a complex electrophoretie p~ttern composed of at least 14 components.No specific electrophoretic changes accompanied the eoagulum characterizing the secondary phase of rennin action on whole casein.Rennin action on casein involves a primary phase during which the protective colloidal properties of K-casein are destroyed (12, 15) and a secondary phase involving the destabilization of the caseinate micelle and formation of a coagulum.A tertiary phase, with slow hydrolysis of the casein components, has been reported by Alais et al. (2).A nondialyzable glycomacropeptide is released from K-casein during the primary phase (1).The material insoluble at pH 4.60 (para-K-casein) either consists of one major and one minor component (2, 3) or two major a~nd one minor component (10, 12), which are positively charged at pI-I 8.60 and migrate towards the cathode.In an acrylamide electropherogram of para-x-casein,
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