Lessley B A, Garner D L
Biol Reprod. 1983 Mar;28(2):447-59. doi: 10.1095/biolreprod28.2.447.
Bovine epididymal or ejaculated semen was fractionated by density gradient centrifugation in Percoll, and seminal components recovered from the gradients were subjected to additional separation and washing steps. This procedure resulted in isolation of four major seminal constituents: particle-free extracellular fluid, washed light particulates, washed cytoplasmic droplets, and washed spermatozoa. When assayed using the Pz-peptide substrate, all the isolated seminal fractions contained substantial Pz-peptidase activity. The extracellular fluid Pz-peptidase was present in soluble form, but Triton X-100 was required for complete extraction of the Pz-peptidase activity from the spermatozoa, cytoplasmic droplets, and light particulates. The greatest Pz-peptidase activities were observed in the cytoplasmic droplet and epididymal sperm extracts, whereas the activities in extracellular fluid, extracts of light particulates, and extracts of ejaculated spermatozoa were relatively low. Most of the Pz-peptidase activity in extracts of epididymal spermatozoa was attributable to cytoplasmic droplets. The specific Pz-peptidase activities found by regression analysis were 6.1 mU/billion attached cytoplasmic droplets and 1.1 mU/billion spermatozoa. These results established that in the bovine, cytoplasmic droplets were the major source of Pz-peptidase activity in semen and that Pz-peptidase was not primarily a spermatozoal enzyme.
牛附睾精液或射出精液通过在Percoll中进行密度梯度离心进行分级分离，从梯度中回收的精液成分经过额外的分离和洗涤步骤。该程序导致分离出四种主要的精液成分：无颗粒细胞外液、洗涤后的轻颗粒、洗涤后的细胞质滴和洗涤后的精子。当使用Pz-肽底物进行测定时，所有分离的精液部分都含有大量的Pz-肽酶活性。细胞外液Pz-肽酶以可溶形式存在，但从精子、细胞质滴和轻颗粒中完全提取Pz-肽酶活性需要Triton X-100。在细胞质滴和附睾精子提取物中观察到最大的Pz-肽酶活性，而细胞外液、轻颗粒提取物和射出精子提取物中的活性相对较低。附睾精子提取物中的大部分Pz-肽酶活性归因于细胞质滴。通过回归分析发现的比Pz-肽酶活性分别为每十亿个附着的细胞质滴6.1 mU和每十亿个精子1.1 mU。这些结果表明，在牛中，细胞质滴是精液中Pz-肽酶活性的主要来源，并且Pz-肽酶不是主要的精子酶。
