J. Biochem, 1976, Vol. 79, No. 6 1235-1243
© 1976 Japanese Biochemical Society
research-article |
Synthesis of Elastin. A Rapid Formation of Lysine-derived Crosslinks by Chick Embryo Aorta
*Department of Agricultural Chemistry, Faculty of Agriculture, Kyoto Prefectural University Shimogamo, Sakyo-ku, Kyoto, Kyoto 606
**School of Dental Medicine, University of Pennsylvania Philadelphia, Pennsylvania, 19174 U.S.A.
Aortas of 13-day-old chick embryo were lebeled for 0.5 hr with [14C]lysine and subjected to a serial extraction after chase for 1–24 hr with [12C]lysine. Substantial radioactivity was found in insoluble elastin after 3 hr chase. The effect of ß-aminopropionitrile on lebeling with [14C]lysine was also examined. Each fraction was hydrolyzed and applied to a short column on an amino acid analyzer. Radioactivity was found in desmosine and isodesmosine of insoluble elastin as early as 1 hr after the beginning of chase. The radioactivity increased rapidly at 2 hr and very slowly thereafter. A large count, which was separated into five peaks on a long column, was observed in other lysine derivatives at 2 hr and increased steadily up to 24 hr, while the lysine count decreased from 1: 0.5 to 1: 6 against lysine derivatives and from 1: 0.04 to 1: 0.9 against quarter-desmosine after 24 hr. The oxidation of lysine residues incorporated during the 0.5 hr pulse was almost completed during the first 1 hr of chase, and these oxidized residues were incorporated into crosslinks during the following 1 hr. It is suggested that poorly crosslinked elastin accumulated in the soluble fractions. The presence of crosslinking derived from lysine residues was also indicated in the microfibril fraction.
1Present address: Department of Food Science and Nutrition, Nara Women's University, Nara, Nara 630-02.