RESUMO
Micellar peroxidase-catalyzed synthesis of chiral polyaniline (PANI) in the presence of dodecylbenzenesulfonic acid (DBSA) was developed. The effect of DBSA concentration on the catalytic efficiency of horseradish and palm tree peroxidases was examined. Favorable conditions for the enzymatic synthesis of chiral PANI, determined by a multiple factors design, demonstrated that the PANIs with the highest chirality were produced in the presence of low concentrations of optically active camphorsulphonic acid (CSA). Unexpectedly, the chiral PANI was also synthesized in the absence of CSA in feed. The favorable conditions for the enzymatic production of chiral and conducting PANIs were shown to be different. The morphology of the chiral PANI particles was examined by transmission and scanning electron microscopies.
Assuntos
Compostos de Anilina/metabolismo , Benzenossulfonatos/química , Cânfora/análogos & derivados , Micelas , Peroxidase/química , Cânfora/química , Catálise , Peroxidase do Rábano Silvestre/química , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , EstereoisomerismoRESUMO
Differential scanning calorimetry was used to study the thermodynamics of denaturation of protein complexes for which the free energy stabilizing the complexes varied between -8 and -16 kcal/mol. The proteins studied were the ribonucleases barnase and binase, their inhibitor barstar and mutants thereof, and complexes between the two. The results are in good agreement with the model developed by Brandts and Lin for studying the thermodynamics of denaturation for tight complexes between two proteins which undergo two-state thermal unfolding transitions.
Assuntos
Endorribonucleases/química , Proteínas/química , Ribonucleases/química , Termodinâmica , Proteínas de Bactérias/química , Estabilidade Enzimática , Ligação Proteica , Desnaturação Proteica , Ribonucleases/antagonistas & inibidoresRESUMO
Human growth hormone (hGH), whose main function is the somatic growth stimulation, induces diverse effects including lactation. We examined the possibility of hGH stabilization by elimination of its lactogenic activity. Chimeric GHs were constructed by replacement of different segments of hGH with sequences derived from non-lactogenic porcine GH. As was observed in the rat Nb2-11C lymphoma cell test, lactogenic activity of some chimeric hormones was seriously destroyed. This kind of hormones displayed the substantial increase in thermal and guanidine hydrochloride stability. The more stable hGH variants were found to be more soluble in Escherichia coli cells.