Identification of the origin of urinary peptides and the assessment of protein nutrition as its application

人的尿液中含有大量的多肽。作者和他的同事已经证明，人体蛋白质降解率或蛋白质总周转率是通过测定这种多肽的排泄率来估算的。如果某些特定的多肽的来源被阐明，并开发出测定它们的方法，它们将为了解原始组织或器官的活性提供非常有用的信息。例如，如果一些癌细胞分泌某些特定的多肽，它们的排泄率就会显示癌细胞的活性。为了测定某些特定多肽的排泄率，本文尝试用毛细管电泳法对这些多肽进行鉴别。首先，采用磷酸盐-硼酸盐缓冲体系或甲酸盐-氨水缓冲体系，用毛细管电泳法分离尿肽。结果表明，尿肽具有很好的分级效果。男性和女性的尿液没有明显的区别。这证实了尿肽反映了人类的基本代谢活动。以大鼠为实验对象，研究了膳食镉对尿肽指纹图谱的影响。膳食镉影响尿肽“指纹”，提示通过尿肽排泄来阐明代谢状态的方法是有效的。

Human urine contains a significant amount of peptides. It has been proved by the present author and his coworkers that the rate of body protein degradation or total turnover rate of body proteins is estimated by determining the rate of this peptide excretion. If the origin of some specific peptides are elucidated and the methods to determine them are developed, they will give very useful information to know the activity, of the original tissues or organs. For example, if some cancer cells excrete some specific peptides, their excretion rate will show the activity of the cancer cells. In order to determine the rate of excretion of some specific peptides, the present author tried to differentiate the peptides by capillary electrophoresis (CE). At first, urinary peptides were differentiated by CE employing phosphate-borate buffer system or formate-ammoinium buffer system. The results showed an excellent fractionation of urinary peptides. There was no clear differentiation between men and women's urine. This confirms that the urinary peptides reflect basic metabolic activity of humans. Employing rats, the effect of dietary cadmium on 'finger print' of urinary peptides were investigated. Dietary cadmium affected the 'fingerprint' of urinary peptides suggesting that the method to elucidate the metabolic status by urinary peptide excretion is valid.