Circular dichroism spectroscopic studies of native and turnover-modified sulfatase A

In a recent communication, A. Waheed and R. L. Van Etten (1979, Arch. Biochem. Biophys. 195, 248) showed that the sulfatase A of rabbit liver (arylsulfate sulfohydrolase, EC 3.1.6.1), which becomes inactivated as it catalyzes the hydrolysis of substrate, covalently incorporates ³⁵S from nitrocatechol ³⁵S]sulfate during this reaction and at the same time loses most of its secondary structure in solution. Circular dichroism spectra presented here for the native and turnover-modified forms of the sulfatase A of ox liver indicate no difference in the region of the spectrum below 240 nm associated with polypeptide backbone contributions or in the region from 350-250 nm associated with the side-chain chromophore transitions. In addition no differences were evident for the two forms of the ox liver enzyme from ultraviolet absorbance and fluorescence spectroscopy measurements. From these data we conclude that, in contrast to the situation with the rabbit enzyme, there is no loss of secondary structure associated with inactivation of ox liver sulfatase A in the course of enzymic catalysis.