Protein significance

Plasma lipid transfer proteins, which include the cholesteryl-ester-transfer-protein (CETP previously known as lipid transfer protein I, LTP-I) and the phospholipid-transfer-protein (PLTP previously known as lipid transfer protein II, LTP-II) mediate the transfer of lipids (cholesteryl esters, triglycerides and phospholipids) between lipoproteins present in human plasma. These proteins significantly affect plasma lipoprotein concentration and composition. 

While crystal structures of rubredoxins have been known since 1970 (for a full review on rubredoxins in the crystalline state, see Ref. (15)), only recently have both crystal and solution structures of Dx been reported (16, 17) (Fig. 3). The protein can be described as a 2-fold symmetric dimer, firmly hydrogen-bonded and folded as an incomplete /3-barrel with the two iron centers placed on opposite poles of the molecule, 16 A apart. Superimposition of Dx and Rd structures reveal that while some structural features are shared between these two proteins, significant differences in the metal environment and water structure exist. They can account for the spectroscopic differences described earlier. 

The SERCA2 homozygous null mouse (—/—) is lethal, but the heterozygous mouse has been useful in assessing the cardiovascular effects of a reduction of SERCA2 protein. Significant alterations in cardiac function were observed (Periasamy et al 1999). However, neither mouse aorta nor portal vein contractility were affected (Weber 1999). We verified that the SERCA protein was indeed reduced so the negative results may indicate that there is a substantial reserve of Ca2+ pump activity. 

Changing the environmental conditions can easily provide sufficient energy to alter the tertiary structure of proteins significantly. 

From PER and net protein ratio (NPR) tests, Palamidis and Markakis (12) later also found that the PER of bread mix (ingredients) or bread mix with 4% nonfat dry milk (NFDM) were 0.75 or 1.17, as compared to 0.46 or 0.75 for their corresponding breads, respectively. The findings also clearly show that baking can damage the nutritive quality of bread protein significantly and that fortification of NFDM can raise the PER of bread mix and wheat (white) bread. 

Limitations for the analysis of hydrophobic proteins—significant for analysis of receptors and ion channels,... 

Some of these compounds have been detected upon thermal decomposition of certain foods, amino acids, and proteins. Significant amounts of compound (13), known as norharman, and its 9-methyl derivative, commonly called harman, have been found in tryptophan pyrolyzates. Similarly, cigarette smoke condensate has been found to contain significant amounts of both of these compounds <82JC331>. 

The basic information of protein tertiary structural class can help improve the accuracy of secondary structure prediction (Kneller et al., 1990). Chandonia and Karplus (1995) showed that information obtained from a secondary structure prediction algorithm can be used to improve the accuracy for structural class prediction. The input layer had 26 units coded for the amino acid composition of the protein (20 units), the sequence length (1 unit), and characteristics of the protein (5 units) predicted by a separate secondary structure neural network. The secondary structure characteristics include the predicted percent helix and sheet, the percentage of strong helix and sheet predictions, and the predicted number of alterations between helix and sheet. The output layer had four units, one for each of the tertiary super classes (all-a, all-p, a/p, and other). The inclusion of the single-sequence secondary structure predictions improved the class prediction for non-homologous proteins significantly by more than 11%, from a predictive accuracy of 62.3% to 73.9%. 

The introduction of hexahistidine tag (Hise-tag) to the N-terminus of chimeric protein significantly simplify the protein purification procedure, enabling isolation of target protein directly from crude cell extract (Efremenko et al, 2006). There were two main tasks in this work was i) to obtain the genetic construct encoding synthesis of fusion protein N-Hise-X-OPH, where X = superecliptic-pH-sensitive fluorine ii) to reveal conditions (host-strain, temperature and inductor concentration) favorable for construct expression in E.coli cells. 

Even thongh Icmt-catalyzed modification only add one carbon to the already isoprenylated cysteine at the C-termini of the target protein, this methylation increases hydrophobicity of the target proteins significantly due to neutralization of the carboxylate anion. Stndies have demonstrated that this modification is important for the fnnction of the relevant proteins, and therefore impacting on ceUnlar fnnctions [24,29-32]... 

Fig. 2 ICAM-1 production after topical application of gamma interferon to a human skin graft on nude mice. One dose (100 pi) of a liposomal (20mg/ml lipid) or aqueous (phosphate buffered saline) formulation was applied daily for three days. Active formulation contained 0.51 mg/ml gamma interferon. Placebo liposomal formulations contained no added protein. Significant differences (active versus placebo) are indicated by asterisks ( ). (Redrawn from data in Ref. l)...

Food can affect both the absorption and the clearance of theophylline. One study showed that the absorption of a modified-release formulation of theophylline was very slow after an overnight fast, in contrast to absorption after a test meal (86). The effect may be dose-related. More specifically, dietary protein significantly affects theophylline clearance a low-protein diet reduces theophylline clearance and a high-protein diet increases it. The implications for clinical practice have not been elaborated, but dietary extremes are contraindicated in patients taking theophylline (51). 

New methods use combined HPLC/Mass spectrometry to identify modified amino acids. Purified recombinant human insulin-like growth factor separated into two peaks on reverse phase HPLC (Cl 8 column/acidified water) even though other methods indicated it was completely pure. Plasma desorption mass spectrometry of the individual peptides detected a single methionine sulfoxide molecule that was sufficient to decrease the hydrophobicity of the whole protein significantly. Most of the oxidation occurred when the secreted fusion protein was cleaved with hydroxylamine under not strictly anaerobic conditions, but about 5% occurred during die . coli fermentation. 

Ricin may inhibit the synthesis of specific proteins to different extents in a myeloma cell line, for example, the synthesis of IgA is inhibited more rapidly than is bulk protein synthesis (Ko and Kaji, 1975). There is currently insufficient experimental evidence, however, to conclude that preferential inhibition of the synthesis of specific proteins significantly influences ricin cytotoxicity in vivo. 

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