EFFECT OF DYNAMIC HIGH-PRESSURE ON THE SECONDARY STRUCTURE OF BETA-LACTOGLOBULIN AND ON ITS CONFORMATIONAL PROPERTIES AS DETERMINED BY FOURIER-TRANSFORM INFRARED-SPECTROSCOPY

The effect of dynamic high pressure on the conformation of beta-lactog lobulin (BLG) has been studied for the first time using Fourier-transf orm infrared spectroscopy. The results show that, whatever the pressur e used (range 0-1400 bar), the conformation-sensitive amide-I band sho ws the maximum absorption at around 1636 cm(-1) proving that beta-shee t is the major structural element. The location of other amide-I compo nent bands are very close in this pressure range, suggesting that dyna mic high pressure has practically no effect on the secondary structure of BLG. However, there are three critical differences between treated and untreated BLG: (i) a different pH sensitivity, (ii) a different t hermostability with treated BLG being thermally more stable than untre ated BLG and (iii) different behavior during the cooling regime of the thermal gelation process. These results suggest that, in spite of hav ing a similar overall conformation, the architecture of BLG before and after dynamic high pressure is stabilized by slightly different inter actions. (C) 1998 Elsevier Science Ltd. All rights reserved.