Biomedical subjects

Hsuan-Liang Liu

Publications and source records attributed to Hsuan-Liang Liu.

21 records · Page 2Linked to original sources

PubMedDate not supplied

Predicted unfolding order of the 13 alpha-helices in the catalytic domain of glucoamylase from Aspergillus awamori var. X100 by molecular dynamics simulations.

The unfolding mechanism of the 13 alpha-helices in the catalytic domain of Aspergillus awamori var. X100 glucoamylase was investigated by 200 ps molecular dynamics simulations in explicit water with temperature jump technique. Rather than a simultaneous event, the unfolding of these 13 alpha-helices followed a random ordered mechanism as alpha8-->alpha1-->alpha11-->alpha7-->alpha10-->alpha3-->alpha12-->alpha13-->alpha4-->alpha5-->alpha9-->alpha6-->alpha2. No significant relationships were found between the unfolding order and the length and the hydrophobicity of the helix. alpha-Helix 8 located in the inner region of the catalytic domain was predicted to be the first helix to unfold, indicating that the destruction of the secondary structure motif was initiated from the inner region of the catalytic domain. The dynamic behavior of these alpha-helices induced by increased kinetic energy during the unfolding process is considered to be similar to the expansion and compression of a series of springs under the influence of mechanical stress.

Amino Acid Sequence↗

PubMedDate not supplied

Molecular dynamics simulations to determine the effect of supercritical carbon dioxide on the structural integrity of hen egg white lysozyme.

In this study, various molecular dynamics simulations were conducted to investigate the effect of supercritical carbon dioxide on the structural integrity of hen egg white lysozyme. The analyses of backbone root-mean-square deviation, radius of gyration, and secondary structure stability all show that supercritical CO(2) exhibits the ability to increase the stability of this protein, probably as a result of the solvent with less polarity, where hydrophobic interactions stabilizing the native structure are weakened and simultaneously the local hydrogen bonds are strengthened, resulting in stabilization of the secondary structures. The hydrophobic cores in the alpha- and beta-domains also play an important role in preventing this protein from thermal unfolding. As supercritical CO(2) has been attractive for biomedical applications because of the advantages of mild critical condition, nonflammability, nontoxity, and the purity of the resulting products, the structural stabilizing effect found in this study strongly suggests that it is possible to increase the thermostability of hen egg white lysozyme by pretreatment with supercritical CO(2), leading to better industrial applications of this protein.

Carbon Dioxide↗

PubMedDate not supplied

Homology model and molecular dynamics simulation of carp ovum cystatin.

In this study, a homology model of carp ovum cystatin was constructed based on the crystal structure of chicken egg white cystatin. The results of amino acid sequence alignment indicate that these two proteins exhibit 36.11% of sequence identity. The resultant homology model reveals that carp ovum cystatin shares similar folds as chicken egg white cystatin, particularly in the conserved regions of Q48-V49-G52 and P98-W99 and the locations of two disulfide bonds, C67-C76 and C90-C110. However, the results of 1 ns molecular dynamics simulations show that carp ovum cystatin exhibits less structural integrity than chicken egg white cystatin in explicit water at 300 K. The relatively hydrophilic Met62 of carp ovum cystatin, corresponding to the hydrophobic Leu68 of human cystatin C and Ile66 of chicken egg white cystatin, may destabilize the hydrophobic core and form a dimeric structure more easily through domain swapping. A total of 16 positively charged residues are equally distributed on the surface of carp ovum cystatin, resulting in agglutination with the negatively charged spermatozoa via electrostatic interaction. Thus, carp ovum cystatin is considered to be important in preventing carp eggs from polyspermy.

Agglutination↗