Disease relevance of guanidine

• Moreover, edema development was coupled with an increase in efficiency of PG extraction with 0.4 M GuHCl [1].
• Guanidinium chloride (GdmCl) unfolding experiments showed that there is only about a 4.2-kjoule/mol difference in delta G 0 between the pig and Thermus MDH [2].

High impact information on guanidine

• Here, we have studied the structure and dynamics of the small enzyme ribonuclease HI (RNase H) in the presence of the chemical denaturant guanidinium chloride (GdmCl) using single-molecule fluorescence microscopy, with a particular focus on the characterization of the unfolded-state ensemble [3].
• Experimental data for the unfolding of cytochrome c and azurin by guanidinium chloride (GuHCl) are used to construct free-energy diagrams for the folding of the oxidized and reduced proteins [4].
• Analysis of the relative population of the U1, U2, and U3 species in 2.0 M GdmCl gives delta-G values for the U3 --> U2 reaction of +0.1 kcal/mol and for the U2 --> U1 reaction of -0.49 kcal/mol [5].
• Urea and GdmCl may mimic chaperones by partially unfolding VDAC and keeping it in an insertion-competent state. "Auto-directed insertion" may ensure both correct targeting and orientation of nascent proteins in vivo [6].
• Recent studies showed that the enzyme rhodanese could be reversibly unfolded in guanidinium chloride (GdmCl) if aggregation and oxidation were minimized [7].

Biological context of guanidine

• Single-molecule fluorescence (Förster) resonance energy transfer (FRET) experiments were performed on surface-immobilized RNase H molecules as a function of the concentration of the chemical denaturant guanidinium chloride (GdmCl) [8].
• Protein denaturation modifies the fluorescence intensity of ANS, a maximum of intensity being detected close to 2 M GdmCl in hydrogenated buffer, which shows the existence of at least one intermediate state populated at the beginning of the unfolding pathway [9].
• Neither exposure of SP1 to GdmCl nor its reduction and alkylation resulted in the appearance of subunits on sodium dodecyl sulfate-polyacrylamide gel electrophoresis [10].
• It demonstrates that increasing the net negative charge of the protein by acetylation of lysines reduces its stability to urea, GuHCl, and heat, but increases its kinetic stability (its thermodynamic stability cannot be measured) towards denaturation by SDS [11].
• Changes of the long lifetime component upon GdmCl-induced denaturation and unfolding of BCAB and alpha-HLA correlate well with overall changes of the protein conformation [12].

Anatomical context of guanidine

• This problem was studied by using radiolabeling in vivo of rat calvaria with [35Sulphate for 2-72 h and a sequential extraction procedure to yield two pools of newly synthesized proteoglycans: one obtained from non-mineralized tissue by extraction with guanidinium chloride (GdmCl) and another obtained only after demineralization with EDTA [13].
• Articular cartilage, cut into 20 microns-thick sections, was extracted with 4 M guanidinium chloride (GuCl) [14].
• Soluble proteoglycans (SPG) were extracted from bovine (BCC) and human (HCC) costal cartilages by the dissociative method using 4 M guanidinium chloride (GuHCl) [15].
• The presence of very low concentrations of the commonly used chemical denaturants, guanidinium chloride (GdmCl) and urea brought about conformational changes in the erythrocyte membrane skeletal protein, spectrin [16].
• It is concluded that, while reductive GuHCl extracts do contain components with antigenic activity that is localized on elastin-associated microfibrils, they have many non-microfibrillar components [17].

Associations of guanidine with other chemical compounds

• Sensitivity to proteolysis and fluorescence emission spectroscopy showed that the toxin unfolded to a much greater extent in 6 M guanidinium chloride (GuHCl) than in 8 M urea [18].
• Loss of activity occurs at lower concentrations of GdnHCl than the structural changes detected by fluorescence or c.d. After denaturation, regain of activity can be observed provided that a reducing agent (dithiothreitol) is present and that the concentration of GdnHCl is lowered by dialysis rather than by dilution [19].
• In the range 0.5-1.5 M GdmCl, significant decreases in the steady-state anisotropy and average lifetime of the intrinsic tryptophan fluorescence occur, as well as a decrease in the rotational correlation time, from 48 to 26 nsec [20].
• Oxidation in 6M guanidinium chloride (GdnHCl) required remarkably low concentrations of glutathione (reduced form, 0.01 mM; oxidized form, 0.002 mM) to be added to the solubilized hIL-6 before the incubation at pH 8.5, and 22 degrees C for 16 h [21].
• Authenticity refers to the optimum pH for catalytic activity, Michaelis constants for starch and maltoheptaose, as well as identical stability toward temperature, pH, and guanidinium chloride (GdmCl) [22].

Gene context of guanidine

• Analysis by acetic acid-urea polyacrylamide gel electrophoresis (PAGE) showed that, in both fractions, four proteins of lower mobility were coeluted with protamine 1 by 23% guanidinium chloride (GuCl) while protamine 2 alone was eluted by 50% GuCl [23].
• The reversible denaturation of apoC-II by guanidinium chloride (GdmCl) proceeded in a sequential fashion [24].
• However, some BSP was also present in GdmCl extracts and, together with a 35 kDa sulphated protein, was released from a bacterial-collagenase digestion of the tissue residue in both non-mineralizing and mineralizing cultures [25].
• Small-angle neutron scattering profiles are presented from phosphoglycerate kinase, in the native form and strongly denatured in 4 M guanidinium chloride (GdnHCl) solution [26].
• At physiologic pH and ionic strength, in the absence of GdmCl, SP1 existed in the form of oligomers of apparent molecular weights of 40 000 to greater than 300 000 [27].

Analytical, diagnostic and therapeutic context of guanidine

• Denaturation was induced by guanidinium chloride (GdmCI) and monitored by circular dichroism (CD) spectropolarimetry without stopped-flow devices [28].
• The folding and thermodynamic properties of metal free (apo) superoxide dismutases (SODs) are systematically analyzed using equilibrium guanidinium chloride (GdmCl) curves and differential scanning calorimetry (DSC) [29].
• Titrations of apo, Cu(I), and Cu(II)Rc with guanidinium chloride (GdmCl) show that the copper ion stabilizes the folded species and remains bound in the completely unfolded state [30].
• Immobilization with a plastic splint reduced the fraction of proteoglycans not extractable with 4 M guanidinium chloride (GdnHCl) [31].
• Highly purified pregnancy-specific beta 1-glycoprotein (SP1) migrated in gel electrophoresis as a homogeneous species and behaved as a single species in 6 mol/l guanidinium chloride (GdmCl), both in the ultracentrifuge and HPLC [27].

References