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A nucleoside diphosphate kinase has been highly purified from baker's yeast, and has been obtained in a crystalline form from an ethanol‐containing medium. During short‐time incubation with [32P]ATP, the enzyme was phosphorylated to an extent of about 3–4 phosphoryl groups per mole of enzyme assuming a molecular weight of 105. This indicates an intermediate phosphorylation of the enzyme. 1‐[32P]Phosphohistidine was shown to be the dominating radioactive degradation product in an alkaline hydrolysate of the 32P‐labelled enzyme. In addition, 3‐[32P]‐phosphohistidine and Ne‐[32P]phospholysine were obtained in small amounts. The results indicate that the amino acid sequence around the reactive 1‐phosphohistidine of the yeast enzyme is different from that of human erythrocytic and bovine liver nucleoside diphosphate kinase. [ABSTRACT FROM AUTHOR]

HL-A antigens comprising 11 different antigenic specificities were isolated after papain solubilization of spleen-cell membrane constituents. During the entire purification procedure, beta(2)-microglobulin appeared together with the HL-A antigens. The highly purified antigens were composed of two polypeptide chains. The large subunit carried the antigenic specificity whereas the small polypeptide chain was very similar, if not identical, to beta(2)-microglobulin. The two HL-A antigen polypeptide chains were held together by noncovalent interactions only, and beta(2)-microglobulin, isolated from urine, could replace the small subunit in forming a complex with the large polypeptide chain. The topographical relationship in the cell membrane between beta(2)-microglobulin and the large HL-A antigen polypeptide chain is unknown. The two polypeptide chains may be fortuitously bound as a result of the solubilization procedure.