The tissue kallikrein-kinin system in human seminal plasma--biochemical and functional aspects

At least three species of tissue kallikrein-like antigens are present in human seminal plasma which differ in their molecular masses and enzymatic activities. At least one of these species is a genuine tissue kallikrein as judged by the criteria of molecular mass, immunoreactivity, inhibition by aprotinin and non-inhibition by soybean trypsin inhibitor, and the ability to release kallidin from kininogen. The prostatic gland was identified as the origin of the seminal fluid tissue kallikrein first by indirect studies and then by demonstrating the presence of immunoreactive tissue kallikrein both in prostatic tissue and secretion.