We have recently reported that electrostatic interactions may play a critical role in alcohol-induced aggregation of alpha-chymotrypsin (CT). In the present study, we have investigated the heat-induced aggregation of this protein. Thermal aggregation of CT obeyed a characteristic pattern, with a clear lag phase followed by a sharp rise in turbidity. Intrinsic and ANS fluorescence studies, together with fluorescence quenching by acrylamide, suggested that the hydrophobic patches are more exposed in the denatured conformation. Typical chaperone-like proteins, including alpha- and beta-caseins and alpha-crystalline could inhibit thermal aggregation of CT, and their inhibitory effect was nearly pH-independent (within the pH range of 7-9). This was partially counteracted by alpha-, beta- and especially gamma-cyclodextrins, suggesting that hydrophobic interactions may play a major role. Loss of thermal aggregation at extreme acidic and basic conditions, combined with changes in net charge/pH profile of aggregation upon chemical modification of lysine residues are taken to support concomitant involvement of electrostatic interactions. Study holds ProTherm entries: 23977 Extra Details: scan rate: 0.25-1 degreesC/min alpha-Chymotrypsin; Thermal aggregation; Hydrophobic interactions; Chaperone-like proteins; Kosmotropic and chaotropic ions
Submitter: Connie Wang
Submission Date: April 24, 2018, 8:55 p.m.
|Number of data points||3|
|Proteins||Chymotrypsinogen A ; Calnexin|
|Assays/Quantities/Protocols||Experimental Assay: dHcal ; Experimental Assay: Tm ; Experimental Assay: dHvH|
|Libraries||Mutations for sequence SKSKPDTSAPTSPKVTYKAPVPSGEVYFADSFDRGTLSGWILSKAKKDDTDDEIAKYDGKWEVDEMKETKLPGDKGLVLMSRAKHHAISAKLNKPFLFDTKPLIVQYEVNFQNGIECGGAYVKLLSKTPELNLDQFHDKTPYTIMFGPDKCGEDYKLHFIFRHKNPKTGVYEEKHAKRPDADLKTYFTDKKTHLYTLILNPDNSFEILVDQSIVNSGNLLNDMTPPVNPSREIEDPEDQKPEDWDERPKIPDPDAVKPDDWNEDAPAKIPDEEATKPDGWLDDEPEYVPDPDAEKPEDWDEDMDGEWEAPQIANPKCESAPGCGVWQRPMIDNPNYKGKWKPPMIDNPNYQGIWKPRKIPNPDFFEDLEPFKMTPFSAIGLELWSMTSDIFFDNFIVCGDRRVVDDWANDGWGLKKAADGAAEP|