Effect of polyamines on thermal inactivation of hen egg white lysozyme

Lysozyme is considered as part of the innate immune system. It has stimulated considerable interest as a natural food preservative. Lysozyme has been shown to be effective in preserving a variety of foods such as fresh fruits and vegetables, meats, seafood and wine, for which many Japanese patents have been granted. The relatively high thermal stability of lysozyme also makes it attractive for use in pasteurized and heat-sterilized food products, possibly allowing reduced thermal processes, and therefore, minimized nutritional and sensory quality loss. In this study, we investigated effect of polyamines on the thermal inactivation of lysozyme by kinetics curves. Our results showed that polyamines can decrease the thermal inactivation of lysozyme; the effect of spermine on the thermal inactivation of lysozyme was more than that of the spermidine

Thermal aggregation of hen egg white lysozyme: effect of polyamines

Protein aggregation is a serious problem for both biotechnology and cell biology. Diseases such as prion misfolding, Alzheimer's, and other amyloidosis are phenomena for which protein aggregation in our living cells is of considerable relevance. Human lysozyme has been shown to form amyloid fibrils in individuals suffering from nonneuropathic systemic amyloidosis, all of which have point mutations in the lysozyme gene. In this study, we investigated effect of small additives on the thermal aggregation of lysozyme. The main finding of this work is that multiple amine groups, spermine and spermidine, play pivotal roles in preventing the thermal aggregation of lysozyme. Our results showed that effect of spermine is more than spermidine

study on the activity and thermal stability of adenosine deaminase in the presence of spermine

Adenosine Deaminase is an amino hydrolase [EC 3.5.4.4] which participates in the purine metabolism where it degrades either adenosine or 2'-deoxyadenosine producing inosine or 2'- deoxy inosine, respectively. The enzyme contains a parallel alpha/beta -barrel motif with eight central beta strands and eight peripheral alpha helices. ADA is located both in the cytosol and on the cell membrane. Since spermine, a natural metabolite, exists in all cells and tissues and its effect on the cell proliferation and enzyme regulation have been reported, thermal inactivation of the ADA and spermine regulatory effect on the ADA activity have been investigated in this study. Percentage of ADA activity in the presence and absence of spermine [1000 microM] in Tris buffer 50 mM, pH 7.5 at physiologic and pathologic temperatures have been reported in the present study. Thermal inactivation curves for ADA in the absence and presence of spermine [1000 microM] in different temperatures ranging from 55 degreeC to 70 degreeC have been drawn. Our data showed that spermine activates the enzyme in the low concentrations of adenosine at 37 degreeC. However, it inhibits ADA activity at 42 degreeC in the same concentrations of substrate. It is concluded that spermine regulatory effect depends on combined influence of temperature and adenosine concentration. Furthermore, thermal stability of the enzyme also depends on temperature in presence of spermine. Binding site of spermine on the enzyme has been identified by docking analysis

L-tryptophan production by Escherichia coli in the presence of Iranian cane molasses

The essential amino acid L-tryptophan [Trp] has importance as a pharmaceutical agent, especially in neuro-medicine. It is also added to feed products as a food fortifier. Furthermore, application of Trp is widespread in biotechnology. Trp is produced by a condensation reaction between indole and Lserine, which is catalyzed by bacterial tryptophan's activity. In this study, we have investigated Trp production using microbial system in the presence and absence of its precursors and Iranian cane molasses. The results showed that the optimum concentration of the molasses for maximum bacterial growth is 10 g/lit. Furthermore, in order to assay the amount of tryptophan produced, thin layer chromatography was used. The results showed that Iranian cane molasses contains considerable amounts of serine and indole, enough for Trp production [0.48 mM] in culture medium. But additional indole has inhibitory effects on Trp production. The data are compatible with previous reports on inhibitory effect of indole not only on cell growth but also on tryptophan's formation and function