Keeley F W, Johnson D J
Can J Biochem Cell Biol. 1983 Oct;61(10):1079-84. doi: 10.1139/o83-136.
The rate of in vitro synthesis of soluble and insoluble elastin by thoracic aorta of 2-day-old chicks has been measured in absolute terms. In the absence of beta-aminopropionitrile (beta APN), the steady state level of soluble elastin was 120 pmol/100 mg of aortic tissue or 3.7 micrograms/whole aorta segment. The rate of synthesis of elastin in vitro was approximately 130 micrograms/day per whole aorta segment. This is three- to four-fold lower than the estimated rate of in vivo synthesis for a comparable segment of aortic tissue at the same stage of development. Pulse-chase experiments suggested that this difference was not due to in vitro proteolysis of a significant proportion of the newly synthesized soluble elastin, but rather that the conversion of soluble to insoluble elastin was both rapid and efficient. These experiments also indicated the presence in aortic tissue of a substantial pool of elastin of intermediate solubility. Although inclusion of beta APN in the incubation medium resulted in an increase in the amount of soluble elastin in aortic tissue, the rate of accumulation of newly synthesized soluble elastin in the presence of this inhibitor of cross-linking was not linear, but decreased with incubation time. Furthermore, although beta APN effectively suppressed the appearance of insoluble elastin for at least 2 h, some escape from the effect of this inhibitor was seen with further incubation. In general, beta APN significantly depressed elastin synthesis.
已对2日龄雏鸡胸主动脉中可溶性和不溶性弹性蛋白的体外合成速率进行了绝对测量。在不存在β-氨基丙腈（βAPN）的情况下，可溶性弹性蛋白的稳态水平为120 pmol/100 mg主动脉组织或3.7 μg/整个主动脉段。体外弹性蛋白的合成速率约为每个整个主动脉段130 μg/天。这比发育相同阶段的主动脉组织可比段的体内合成估计速率低三到四倍。脉冲追踪实验表明，这种差异不是由于新合成的可溶性弹性蛋白的很大一部分在体外被蛋白水解，而是可溶性弹性蛋白向不溶性弹性蛋白的转化既迅速又有效。这些实验还表明主动脉组织中存在大量具有中等溶解度的弹性蛋白池。虽然在孵育培养基中加入βAPN会导致主动脉组织中可溶性弹性蛋白的量增加，但在这种交联抑制剂存在下新合成的可溶性弹性蛋白的积累速率不是线性的，而是随孵育时间而降低。此外，虽然βAPN有效地抑制了不溶性弹性蛋白的出现至少2小时，但随着进一步孵育，可观察到一些弹性蛋白逃脱了这种抑制剂的作用。一般来说，βAPN显著抑制弹性蛋白的合成。
