Amino acid composition and electrophoretic properties of hypertensin I.

A preparation of hypertensin I was purified by countercurrent distribution and was shown to migrate as a single component in starch blocks at pH 9.3 and 4.2.

The purification of hypertensin I.

The purification of hypertensin I has been described. The final product which is four times as powerful a pressor agent as l-arterenol, is obtained with an over-all recovery of 40 per cent. The product consists of a single component in countercurrent distribution, having a nitrogen content of 15.

The existence of two forms of hypertensin.

Two types of hypertensin have been demonstrated by means of counter-current distribution. The first type is the product of the action of the enzyme, renin, upon its substrate and has been designated hypertensin I. It can be rapidly converted to a second approximately equally pressor compound, hypertensin II, apparently through the action of an enzyme in the plasma which requires halide or nitrate for activation.