Acid phosphomonoesterase of human prostate. Carbohydrate content and optical properties

Human prostatic acid phosphatase I, a glycoprotein, has been analyzed with respect to its quantiative carbohydrate composition and its fluorescence, optical rotatory and circular dichroic spectra. The protein of 89 000 molecular weight has 38 to 41 carbohydrate residues attached, of which 3 residues are fucose, 4 are galactose, 11 mannose, 15 glucosamine and there are 7 to 8 residues of sialic acid. The native glycoprotein contains about 30% alpha-helix as estimated from the rotational and dichroic spectra. Upon removal of sialic acid by neuraminidase treatment, there is a small increase in this value, while the fluorescence intensity at he emission maximum (357 nm) is distinctly increased. These effects suggest that an interaction exists of the sialic acid group with parts of the native protein. Allowance is made for the contribution of the carbohydrate components in interpreting the spectra in structural terms.