Study of kinetics of thermal aggregation of mitochondrial aspartate aminotransferase by dynamic light scattering: protective effect of α-crystallin

Abstract

Thermal aggregation of aspartate aminotransferase from pig heart mitochondria (mAAT) has been studied at various temperatures and various protein concentrations by dynamic light scattering. The character of the dependence of protein aggregate size on time indicates that aggregation of mAAT proceeds in the regime of diffusion-limited cluster-cluster aggregation. Suppression of mAAT aggregation by alpha-crystallin is due to transition of the aggregation process into the regime of reaction-limited cluster-cluster aggregation. Realization of this regime of aggregation means that the sticking probability for the colliding particles is less than unity.

Arginine controls heat‐induced cluster–cluster aggregation of lysozyme at around the isoelectric point

“…[38][39][40] In fact, the addition of Arg resulted in the formation of denser aggregates than those in the absence of solution additives (see Figure 4). It is worth mentioning that a-crystallin 33,35,37 and GroEL 53 change the regime of protein aggregation from DLCA to RLCA. Both a-crystallin 56,57 and GroEL 58,59 prevent protein aggregation by stabilization of denatured protein via complexation.…”

“…These observations indicated that start aggregates of protein appeared and the formation of the start aggregates proceeded as all-ornone principle without accumulation of intermediates, consistent with previous reports. [33][34][35][36][37] The mean value of the aggregate sizes changed toward the higher R h value with increasing incubation time. At t 5 16 min, no monomeric ly- sozyme was detected.…”

“…aggregation is described by the kinetic theory of colloid particle aggregation, that is, the start aggregates stick together in the diffusion-limited cluster-cluster aggregation (DLCA) regime. [33][34][35][36][37] DLCA occurs when there is no repulsive force between colloidal particles, and hence the aggregation rate is only dependent on the time for particles to collide by diffusion. 38,39 In this study, we investigated the process of protein aggregation in the presence of arginine using DLS.…”

“…Analysis of the kinetics of protein aggregation in the absence of solution additives have demonstrated two-step aggregation using DLS. [33][34][35][36][37] Briefly, the first step of aggregation is the formation of a ''start aggregate'' with a hydrodynamic radius (R h ) of tens to hundreds of nanometers; the second step of aggregation is the further growth of the aggregates as the primary clusters by their sticking together. The second step of protein Arginine Controls Heat-Induced Cluster-Cluster Aggregation of Lysozyme at Around the Isoelectric Point Additional supporting information may be found in the online version of this article.…”

Mechanism of suppression of dithiothreitol-induced aggregation of bovine α-lactalbumin by α-crystallin

“…The hydrodynamic radius of the start aggregates was tens of nanometers. The start aggregate formation was revealed in the process of thermal aggregation of the following model substrates: β L -crystallin from bovine lens [1], glyceraldehyde-3-phosphate dehydrogenase and glycogen phosphorylase b from rabbit skeletal muscle [2][3][4][5][6], aspartate aminotransferase from pig heart mitochondria [7] and tobacco mosaic virus coat protein [8].…”