›› 2003, Vol. 46 ›› Issue (3): 277-281.

• 研究论文 • 上一篇    下一篇

家蚕体内维生素B6的存在形态和转换代谢

张剑韵, 黄龙全   

  • 出版日期:2003-06-20 发布日期:2003-06-20

Distribution, movement and metabolism of vitamin B6 compounds in the silkworm, Bombyx mori

ZHANG Jian-Yun, HUANG Long-Quan   

  • Online:2003-06-20 Published:2003-06-20

摘要: 采用不含桑叶粉末、以去维生素牛乳酪蛋白为蛋白源的准合成饲料饲育家蚕Bombyx mori幼虫,探讨了家蚕体内维生素B(VB6)化合物的存在形态和转换代谢途经。随饲料中盐酸吡哆醇(PN-HCl)添加量的增加,幼虫体内吡哆醇(PN)含量相应变化,其次是吡哆醛(PL);而辅酶型磷酸吡哆醛(PLP)和磷酸吡哆胺(PMP)含量存在稳定性。饲料中的吡哆醇以单纯扩散的形式进入体液;体液中的吡哆醇被各种组织吸收后,在各自的吡哆醛激酶和PNP/磷酸吡哆胺氧化酶的作用下,转变成辅酶型磷酸吡哆醛。家蚕不同于哺乳动物,没有特定的辅酶型磷酸吡哆醛形成组织和辅酶型磷酸吡哆醛的转送机制。同时家蚕体内缺乏具储存VB6功能的辅酶型磷酸吡哆醛结合蛋白,推测这是用缺乏VB6的饲料饲育各龄起蚕,幼虫当龄死亡的主要原因。

关键词: 家蚕, 准合成饲料, 维生素B6, 存在形态, 转换代谢

Abstract: The distribution, movement and metabolism of vitamin B6 (VB6) compounds in the silkworm, Bombyx mori, were studied in larvae reared on a semisynthetic diet, in which there was no mulberry powder and vitamin-free casein was the protein source. With the increase in the pyridoxine hydrochloride (PN-HCl) content of the diet, pyridoxine (PN) accumulated, and the content of pyridoxal (PL) increased in the larval body. However, the contents of (PLP) and yridoxamine 5'-phosphate (PMP), both of which are the coenzyme forms of VB6, remained almost constant. PN absorbed by the midgut was first diffused into the hemolymph and then distributed to other organs by active transport. PN was first phosphorylated to pyridoxine 5'phosphate (PNP) by PL kinase, which was then oxidized to PLP by PNP/PMP oxidase in every larval organ except hemolymph. The transportation system of PLP, in which PLP binds to albumin, in the mammalian blood does not exist in silkworms. It is thus thought that the distribution, movement and metabolism of VB6 compounds are different from those of mammals, and these are the reasons why almost no larvae could reach the next instar when newly molted larvae were reared on a VB6 deficient diet.

Key words: Bombyx mori, semisynthetic diet, vitamin B 6, distribution, metabolism