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Hiroyuki Hamada
University of Tsukuba
16Publications
7H-index
335Citations
Publications 16
Newest
#1Tsuneyoshi Matsuoka (University of Tsukuba)H-Index: 4
#2Hiroyuki Hamada (University of Tsukuba)H-Index: 7
Last.Kentaro Shiraki (University of Tsukuba)H-Index: 27
view all 4 authors...
This article investigates solution additives that prevent misfolding of lysozyme from heating treatment and during refolding processes. Comparison of heat treatment of native lysozyme and oxidative refolding from the reduced and denatured state of lysozyme in the presence of 44 different additives revealed an indispensable chemical structure for the additives to be effective against heat-induced misfolding and for refolding. The additives effective against heat treatment of native lysozyme posse...
#1Hiroyuki HamadaH-Index: 7
#2Tsutomu ArakawaH-Index: 45
Last.Kentaro Shiraki (University of Tsukuba)H-Index: 27
view all 3 authors...
This paper overviews solution additives that affect protein stability and aggregation during refolding, heating, and freezing processes. Solution additives are mainly grouped into two classes, i.e., protein denaturants and stabilizers. The former includes guanidine, urea, strong ionic detergents, and certain chaotropic salts; the latter includes certain amino acids, sugars, polyhydric alcohols, osmolytes, and kosmotropic salts. However, there are solution additives that are not unambiguously pla...
#1Atsushi Hirano (University of Tsukuba)H-Index: 15
#2Hiroyuki Hamada (University of Tsukuba)H-Index: 7
Last.Kentaro Shiraki (University of Tsukuba)H-Index: 27
view all 3 authors...
Although solution additives prevent protein misfolding, the mechanism remains elusive. In this paper, we compare the preventive effects of trans-1,2-cyclohexanediamine (1,2-CHDA) and trans-1,4-cyclohexanediamine (1,4-CHDA) on the heat-induced inactivation of ribonuclease A (RNase A) and lysozyme. These additives are more effective in preventing thermal inactivation of the proteins than guanidine (Gdn) and arginine (Arg). The results suggest two possibilities: (i) decrease in the hydrophobic inte...
#1Hiroyuki Hamada (University of Tsukuba)H-Index: 7
#2Ryouta Takahashi (University of Tsukuba)H-Index: 11
Last.Kentaro Shiraki (University of Tsukuba)H-Index: 27
view all 4 authors...
Although a number of low-molecular-weight additives have been developed to suppress protein aggregation, it is unclear whether these aggregation suppressors affect various aggregation processes in the same manner. In this study, we evaluated the differences in the effect of solution additives on heat- and refolding-induced aggregation in the presence of guanidine (Gdn), arginine (Arg), and spermidine (Spd), and the comparable analysis showed the following differences: (i) Gdn did not suppress th...
#1Shunsuke Tomita (University of Tsukuba)H-Index: 12
#2Hiroyuki Hamada (University of Tsukuba)H-Index: 7
Last.Kentaro Shiraki (University of Tsukuba)H-Index: 27
view all 4 authors...
Abstract. Arginine (Arg) is a commonly used additive to prevent protein aggregation and inactivation in denaturing solutions. This paper presents new findings on the synergistic effect on the prevention of heat-induced aggregation of lysozyme using Arg in combination with polyethylene glycol (PEG). The synergistic enhancement was observed in the presence of Arg with amphiphilic polymers, such as PEG6000, PEG20000, and poly(vinyl pyrrolidone), while it was not observed with hydrophilic polymers, ...
#1Atsushi Hirano (University of Tsukuba)H-Index: 15
#2Hiroyuki Hamada (University of Tsukuba)H-Index: 7
Last.Kentaro Shiraki (University of Tsukuba)H-Index: 27
view all 6 authors...
Protein aggregation is a critical problem for biotechnology and pharmaceutical industries. Despite the fact that soluble proteins have been used for many applications, our understanding of the effect of the solution chemistry on protein aggregation still remains to be elucidated. This paper investigates the process of thermal aggregation of lysozyme in the presence of various types of salts. The simple law was found; the aggregation rate of lysozyme increased with increasing melting temperature ...
#1Hiroyuki Hamada (University of Tsukuba)H-Index: 7
#2Kentaro Shiraki (University of Tsukuba)H-Index: 27
Abstract l -Arginine (Arg) is a widely used additive for suppressing protein aggregation during refolding. Systematic screening of Arg analogs provides superior additives that enhance the refolding yield more effectively than Arg. The refolding yield of hen egg lysozyme in the presence of 500 mM l -argininamide (ArgAd) increases 1.7-fold higher than Arg. Thermal unfolding experiments indicate that ArgAd has a greater denaturing effect than Arg. The refolding yield positively relates to the net c...
#1Tsuneyoshi Matsuoka (University of Tsukuba)H-Index: 4
#2Shunsuke Tomita (University of Tsukuba)H-Index: 12
Last.Kentaro Shiraki (University of Tsukuba)H-Index: 27
view all 4 authors...
An additive that is highly effective in small amounts for controlling protein inactivation and aggregation has long been demanded. In this paper we show amidated amino acids as new potent additives. In the presence of 100 mM amidated amino acids, e.g., Ala, Arg, Asn, Met, and Val, the heat-induced inactivation and aggregation of lysozyme at pH 7.1 are one order of magnitude slower than those in the absence of additives. Although a high Arg concentration (>1 M) has been used to prevent aggregatio...
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