Adsorption-Induced Changes in Ribonuclease A Structure and Enzymatic Activity on Solid Surfaces

Ribonuclease A (RNase A) is a small globular enzyme that lyses RNA. The remarkable solution stability of its structure and enzymatic activity has led to its investigation to develop a new class of drugs for cancer chemotherapeutics. However, the successful clinical application of RNase A has been reported to be limited by insufficient stability and loss of enzymatic activity when it was coupled with a biomaterial carrier for drug delivery. The objective of this study was to characterize the structural stability and enzymatic activity of RNase A when it was adsorbed on different surface chemistries (represented by fused silica glass, high-density polyethylene, and poly­(methyl-methacrylate)). Changes in protein structure were measured by circular dichroism, amino acid labeling with mass spectrometry, and in vitro assays of its enzymatic activity. Our results indicated that the process of adsorption caused RNase A to undergo a substantial degree of unfolding with significant differences in its adsorbed structure on each material surface. Adsorption caused RNase A to lose about 60% of its native-state enzymatic activity independent of the material on which it was adsorbed. These results indicate that the native-state structure of RNase A is greatly altered when it is adsorbed on a wide range of surface chemistries, especially at the catalytic site. Therefore, drug delivery systems must focus on retaining the native structure of RNase A in order to maintain a high level of enzymatic activity for applications such as antitumor chemotherapy

Inhibitory Activity of Carbonyl Compounds on Alcoholic Fermentation by Saccharomyces cerevisiae

Aldehydes and acids play important roles in the fermentation inhibition of biomass hydrolysates. A series of carbonyl compounds (vanillin, syringaldehyde, 4-hydroxybenzaldehyde, pyrogallol aldehyde, and <i>o</i>-phthalaldehyde) were used to examine the quantitative structure–inhibitory activity relationship of carbonyl compounds on alcoholic fermentation, based on the glucose consumption rate and the final ethanol yield. It was observed that pyrogallol aldehyde and <i>o</i>-phthalaldehyde (5.0 mM) reduced the initial glucose consumption rate by 60 and 89%, respectively, and also decreased the final ethanol yield by 60 and 99%, respectively. Correlating the molecular descriptors to inhibition efficiency in yeast fermentation revealed a strong relationship between the energy of the lowest unoccupied molecular orbital (<i>E</i>_LUMO) of aldehydes and their inhibitory efficiency in fermentation. On the other hand, vanillin, syringaldehyde, and 4-hydroxybenzaldehyde (5.0 mM) increased the final ethanol yields by 11, 4, and 1%, respectively. Addition of vanillin appeared to favor ethanol formation over glycerol formation and decreased the glycerol yield in yeast fermentation. Furthermore, alcohol dehydrogenase (ADH) activity dropped significantly from 3.85 to 2.72, 1.83, 0.46, and 0.11 U/mg at 6 h of fermentation at vanillin concentrations of 0, 2.5, 5.0, 10.0, and 25.0 mM correspondingly. In addition, fermentation inhibition by acetic acid and benzoic acid was pH-dependent. Addition of acetate, benzoate, and potassium chloride increased the glucose consumption rate, likely because the salts enhanced membrane permeability, thus increasing glucose consumption

Straw blood cell count, growth, inhibition and comparison to apoptotic bodies-2

Bular transformation induced by dehydration. DNA ladder did appear (right panel) in CACO2 cells during a failed tubular transformation . Measurement of caspase-3/7 activity during dehydration induced tubular transformation in CACO2 cells. . Inhibition of tubular transformation by small molecules in vivo. Blood samples are counted from a single dose sc at 24 hr.<p><b>Copyright information:</b></p><p>Taken from "Straw blood cell count, growth, inhibition and comparison to apoptotic bodies"</p><p>http://www.biomedcentral.com/1471-2121/9/26</p><p>BMC Cell Biology 2008;9():26-26.</p><p>Published online 20 May 2008</p><p>PMCID:PMC2397387.</p><p></p

Straw blood cell count, growth, inhibition and comparison to apoptotic bodies-4

2 cells that were transformed into straw cells. . Regeneration of regular cells from straw cells, three proteins at 63, 57, and 52 KD were abundantly expressed in the early stage of the process.<p><b>Copyright information:</b></p><p>Taken from "Straw blood cell count, growth, inhibition and comparison to apoptotic bodies"</p><p>http://www.biomedcentral.com/1471-2121/9/26</p><p>BMC Cell Biology 2008;9():26-26.</p><p>Published online 20 May 2008</p><p>PMCID:PMC2397387.</p><p></p