Radioiodination of tyrosine residue(s) of ox testis and of wheat germ calmodulins.
Radioiodination of the two tyrosine residues (Tyr-99 and Tyr-138) of ox testis calmodulin was performed using several methods, and studied through the specific activity, and the [125I]iodoamino acid analysis of the radiolabeled calmodulins. Hydrolysis by thrombin of 125I-calmodulin labeled by the lactoperoxidase method and subsequent isolation of peptides TM1 and TM2 by gel electrophoresis showed preferential labeling by 125I of Tyr-99 (TM1) over Tyr-138 (TM2). Analysis of [125I]iodoamino acids of radiolabeled TM1, TM2 and calmodulin demonstrated that [125I]monoiodotyrosine was predominant, the remainder being [125I]diiodotyrosine. Radioiodination of wheat germ calmodulin, which contains a single tyrosine residue (Tyr-139), showed that only TM2 was labeled by 125I on the Tyr-139 residue and also on the His-108 residue (radiolabeled monoiodotyrosine, diiodotyrosine and monoiodohistidine being present).
C
C
Dutoit
M
M
Rolland
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R
Aquaron
D000818:Animals; D002147:Calmodulin / Q000032:analysis; D002417:Cattle; D002700:Chloramines; D007457:Iodine Radioisotopes; D007553:Isotope Labeling / Q000379:methods*; D007784:Lactoperoxidase; D008297:Male; D007470:Monoiodotyrosine / Q000032:analysis; D010446:Peptide Fragments; D010944:Plants / Q000032:analysis*; D013737:Testis / Q000032:analysis*; D013917:Thrombin; D014105:Tosyl Compounds; D014908:Triticum; D014443:Tyrosine; D014508:Urea / Q000031:analogs & derivatives
D002147:Calmodulin; D002700:Chloramines; D007457:Iodine Radioisotopes; D010446:Peptide Fragments; D014105:Tosyl Compounds; C016300:chloramine-T; D014443:Tyrosine; C012385:1,3,4,6-tetrachloro-3 alpha,6 alpha-diphenylglycoluril; D014508:Urea; D007784:Lactoperoxidase; D013917:Thrombin; D007470:Monoiodotyrosine