SECONDARY STRUCTURE OF HOLO-AMINOACYLASE AND APO-AMINOACYLASE FROM PREDICTION, CIRCULAR-DICHROISM, AND FT-RAMAN SPECTROSCOPY

The secondary structures of native (Holo-) and Zn2+-free (Apo-) aminoa cylase were examined by circular dichroism (CD) and Fourier transform- Raman (FT-Raman) spectroscopic techniques and prediction methods, Quan titative analysis of the conformationally sensitive amide I band indic ates that Holo- and Ape-enzyme contain 19.3 and 17.2% helical structur e, respectively, Far-UV CD spectra of Holo- and Ape-enzyme show that t hey contain 20.1 and 17.6% alpha-helix, respectively, Secondary struct ure prediction of aminoacylase indicates that it contains approximatel y 20.9% alpha-helical structure including 10 alpha-helix segments, The results show that after removal of Zn2+ in aminoacylase, the extent o f ordered structure was decreased markedly, The conformation at or nea r the active site of aminoacylase may contain more ordered structure a nd the presence of Zn2+ may help to maintain the catalytically active conformation at the active site.