Elucidation of Prorerties and Physiological Roles of nicoinamide-Biding Protein, and It's Applocation to the Determination of Vitamin

已知对每种维生素具有特异性的各种维生素蛋白（BP），但对游离烟酸（NiA）或游离烟酰胺（NAm）具有特异性的BP尚不清楚。因此，我们研究了这种蛋白质，最终我们发现了NAm特异性BP（NAm-BP）。因此，这种蛋白质在猪肝和大鼠的各种器官中的各种特性，以及烟酸相关化合物的影响进行了研究。实验结果表明，在自由采食NAm缺乏、对照和过量NAm的实验饲料2周后，测定NAm-BP的活性。几乎所有器官包括肝脏和肾脏的活性均高于对照组。提示NAm-BP结合NAm的能力随体内NAm含量的变化而变化。在猪肝提取物中也发现了结合的辅因子，其性质如下：分子量，小于10000 ;稳定性，热稳定;酸和碱不稳定;电荷，中性。当加入过量NAm时，NAm-BP上的NAm发生交换。MNA和2-Py使NAm结合能力显著降低。由于这些化合物都是以NAm催化剂的终产物形式从尿中排出，因此推测NAm是随着体内NAm的减少而提供的，但由于时间的限制，未能将NAm-BP用于维生素的测定。

Various vinding proteins (BP) specific to each vitamin are kyown, but the BP specific to free nicotinic acid(NiA) or free nicotinamide (NAm) is not known. Accordingly we investigated such protein and finally we have just found NAm specific BP (NAm-BP). Hence various properties of this protein in hog liveer and in various organs in rat, and effects of niacin-related compounds were investigated. As the results, followings are confirmed.After the experimental diets of NAm-deficient, control, and excess NAm are fed to rats for 2 weeks ad libitum, the activities of NAm-BP were determined. the activities in almost all organs including liver and kidney were higher than those in organs of control group. It is suggested that the ability of NAm binding of NAm-BP is changed according to the amount of NAm in bodies. Cogactor for the binding was also found in the extract from hog liver and the properties of it were as follows : molecular weight, less than 10000 ; stability, heat stable ; acid and aldali labile ; charge, neutral. Exchange of NAm on NAm-BP was obseved when exess NAm was added. NAm-bindin ability was greately lowered with MNA and 2-Py. As these compounds were excreted in urine as final products from NAm catabolism, it is suggested tha NAm is supplied according to the decrease of NAm in the body.Application of this NAm-BP to the determination of vitamin could not be done, because of shortage of time.