英国《BMC生物技术》杂志刊登一项报告说，美国研究人员发明了用玉米制造出可用于人类的胶原蛋白，其优点是安全、成本低。

据介绍，胶原蛋白是人和许多动物体内都含有的一种蛋白质，用途包括手术后敷在伤口上止血、美容上用于修复皮肤凹痕以及用于制作口服保健品等。现在人们常从动物组织中提取胶原蛋白，但使用动物胶原蛋白的问题是，它们给人体造成感染的风险较大，成本也较高。

相比之下来源于植物的胶原蛋白感染风险较小，但需要解决的一个问题是，源于植物的蛋白质需要经过名为羟基化的过程，才能成为可在人体中正常发挥功能的胶原蛋白。美国艾奥瓦州立大学等机构的研究人员报告说，他们通过向玉米中加入一个基因解决了这个问题，这样的转基因玉米可以直接用来制造能用于人类的胶原蛋白。

研究人员说，玉米易于种植、储存和加工处理，用玉米制造胶原蛋白，与从动物组织中提取胶原蛋白相比成本更低，因此本次成果为生产胶原蛋白提供了一个较好的替代来源。（生物谷Bioon.com）

BMC Biotechnology    doi:10.1186/1472-6750-11-69

Hydroxylation of recombinant human collagen type I alpha 1 in transgenic maize co-expressed with a recombinant human prolyl 4-hydroxylase

Xing Xu , Qinglei Gan , Richard C Clough , Kamesh M Pappu , John A Howard , Julio A Baez  and Kan WangBackground

Collagens require the hydroxylation of proline (Pro) residues in their triple-helical domain repeating sequence Xaa-Pro-Gly to function properly as a main structural component of the extracellular matrix in animals at physiologically relevant conditions. The regioselective proline hydroxylation is catalyzed by a specific prolyl 4-hydroxylase (P4H) as a posttranslational processing step.

Results

A recombinant human collagen type I alpha-1 (rCIalpha1) with high percentage of hydroxylated prolines (Hyp) was produced in transgenic maize seeds when co-expressed with both the alpha- and beta- subunits of a recombinant human P4H (rP4H). Germ-specific expression of rCIalpha1 using maize globulin-1 gene promoter resulted in an average yield of 12 mg/kg seed for the full-length rCIalpha1 in seeds without co-expression of rP4H and 4 mg/kg seed for the rCIalpha1 (rCIalpha1-OH) in seeds with co-expression of rP4H. High-resolution mass spectrometry (HRMS) analysis revealed that nearly half of the collagenous repeating triplets in rCIalpha1 isolated from rP4H co-expressing maize line had the Pro residues changed to Hyp residues. The HRMS analysis determined the Hyp content of maize-derived rCIalpha1-OH as 18.11%, which is comparable to the Hyp level of yeast-derived rCIalpha1-OH (17.47%) and the native human CIa1 (14.59%), respectively. The increased Hyp percentage was correlated with a markedly enhanced thermal stability of maize-derived rCIalpha1-OH when compared to the non-hydroxylated rCIalpha1.

Conclusions

This work shows that maize has potential to produce adequately modified exogenous proteins with mammalian-like post-translational modifications that may be require for their use as pharmaceutical and industrial products.