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We used bovine cornea as starting material,pepsin treatment in acetic acid solution to extract the mixture of type Ⅰ and Ⅴ collagens,and salt precipitation and dialysis to purify and isolate each type of the collagens.The preparation was analyzed using sodium dodecyl sulphate polyacrylamide gel electrophoresis.2-mercaptoethanol used as reducing agent cut off the disulfide bonds,which was utilized to analyze the structure of disulfide bonds involved between α chains in some types of collagens.At the same time,we discovered that the structure of disulfide bonds among α chains potentially existed in the type Ⅴ collagen prepared from the pepsin-treatment extraction at 4℃.Through quantitative analysis,we obtained that,compared with those pepsin-treated at 4℃,the relative molecular weights ofα 1 (Ⅴ) and 2 (Ⅴ) subunits pepsin-treated at room temperature decreased by 4.6％ and 6.0％,respectively.It is concluded that type Ⅴ collagen can be prepared from bovine cornea by use of pepsin treatment,salt precipitation and dialysis. The interchain and/or intermolecular disulfide bonds potentially lie near the edges of termini of type Ⅴ collagen molecules existing in extracellular matrix,and there are few of the intermolecular and/or intramolecular crosslinks formed by lysine or hydroxylysine or histidine residues in type Ⅴ collagen.