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Related Topics I: Charge-Transfer Complexes in Biological Systems
Published in Jean-Pierre Farges, Organic Conductors, 2022
Vivian C. Flores, Hendrik Keyzer, Cissy Varkey-Johnson, Karen Leslie Young
Methyglyoxal has been found [246] to bind to structural proteins of beef liver. A very active and widespread enzyme, glyoxalase [247], transforms methylglyoxal efficiently to d-lactic acid. If this were the sole purpose of glyoxalase, a puzzle would exist because methylglyoxal and d-lactic acid together lie on no presently known metabolic pathway. However, the problem acquires a solution when solid-state concepts of charge transfer and electronic desaturation are applied to proteins interacting with methylglyoxal. Proteins suspended in water in the dark with methylglyoxal assume a stable brown color, and the dc conductivity increases by two orders of magnitude [248]. Large ESR signals are observed [248]. Methyglyoxal binds to form colored complexes with bovine serum albumin (BSA), casein, lysozyme, chymotrypsin, chymotrypsinogen, cytochrome c, and fibrinogen [248-250], Lorand showed [251] that all the arginine and 85% of the lysine groups in these proteins are involved in the interaction with methylgloxal. It has further been shown by Pethig and colleagues [248] that the color and electron spin resonance signal intensities are directly related to the number of unblocked lysine groups.
Reversed-Phase and Hydrophobic Interaction Chromatography of Peptides and Proteins
Published in Juan A. Asenjo, Separation Processes in Biotechnology, 2020
Ziad El Rassi, Ann L. Lee, Csaba Horváth
The ionization of the inogenic functions in the protein molecule and concomitantly its three-dimensional structure is affected by the pH of the medium. Therefore, changing the pH of the eluant is also expected to affect the selectivity of protein separations in HIC. Kato et al. (1984b) found that the retention of proteins varied with the pH, but only slightly. Whereas the retention of lysozyme and α-chymotrypsin was almost invariable in the pH range 2 to 8, the retention of α-chymotrypsinogen and ovalbumin increased with decreasing pH of the eluant and the retention of ribonuclease and myoglobin increased with pH. Engelhardt and Schön (1986) have found that lipase was strongly retained on an amide column at pH 5.5, which corresponds to its isoelectric point, whereas the retention of basic proteins was smallest at pH 7.0 and increased with decreasing pH. These observations illustrate the difficulties at present in trying to predict the optimal pH for protein separation by HIC.
Lyophilization of Protein Pharmaceuticals
Published in Kenneth E. Avis, Vincent L. Wu, Biotechnology and Biopharmaceutical Manufacturing, Processing, and Preservation, 2020
John F. Carpenter, Byeong S. Chang
To date, GCSF is the only example from literature, or from unpublished studies on numerous proteins, of an unprotected protein that does not unfold during lyophilization. All other proteins are unfolded (nonnative, but not a random coil associated with complete denaturation) in the dried solid, but display two different behaviors during rehydration. The protein regains the native conformation upon rehydration (reversible unfolding), as observed for α-lactalbumin, lysozyme, chymotrypsinogen, ribonuclease, β-lactoglobulins A and B, α-chymotrypsin, and subtilisin (Prestrelski, Tedeschi, et al. 1993a; Dong et al. 1995; Dong and Carpenter, unpublished observations).The protein aggregates upon rehydration (irreversible unfolding), as noted for LDH, PFK, interferon-gamma, basic fibroblast growth factor, and interleukin-2 (Prestrelski, Tedeschi, et al. 1993; Prestrelski, Arakawa, et al. 1993; Prestrelski et al. 1995; Dong et al. 1995).
Analysis of hydrolytic differences of free and “polyacrylic acid (PAAc)-conjugated trypsin and chymotrypsin” by using fluorescence lifetime distributions
Published in Preparative Biochemistry & Biotechnology, 2020
Ümmügülsüm Polat, İbrahim Ethem Özyiğit, Emine Karakuş
Trypsin and chymotrypsin in the proteolytic enzyme group are synthesized as inactive zymogen enzymes (trypsinogen and chymotrypsinogen) to avert undesirable breaking down of cellular proteins, and to regulate when and where enzyme activity occurs. These inactive zymogens are released into the duodenum, which is the peristaltic movement of the small and large intestines before being thrown away. Moreover, zymogens enter the bloodstream, where they can be found in serum prior to excretion in urine. Zymogens are turned into an active enzyme by proteolysis to split off a pro-peptide, either in a subcellular division or in an extracellular division where they are required for digestion. Although trypsin and chymotrypsin are structurally very similar, they bind different substrates. While trypsin has an effect on lysine and arginine residues, chymotrypsin acts on large hydrophobic residues such as tryptophan, tyrosine, and phenylalanine.[4]
Lipopolysaccharide removal affinity matrices based on novel cationic amphiphilic peptides
Published in Preparative Biochemistry & Biotechnology, 2021
Mina Sepahi, Shahin Hadadian, Reza Ahangari Cohan, Dariush Norouzian
Cationic antimicrobial peptides (CAPs) with high affinity to LPS and low cytotoxicity for mammalian cells have been used for highly effective LPS removal.[9,11] Human LPS-binding proteins (hLBP) immobilized on polyhydroxybutyrate (PHB) particles have been used for LPS removal.[11] Ding et al immobilized a modified form of S3 peptide, to agarose support containing diaminodipropylamine (DADPA) linker and removed LPS from bovine serum albumin (BSA), ovalbumin, and R-chymotrypsinogen as model proteins.[9] S3 peptide is a 34 amino acids CAP derived from the LPS binding site of horseshoe crab factor C and binds to the lipid A part of LPS through electrostatic and hydrophobic interactions.[18] In our previous work, we designed two new variants of S3 peptide for chemo-selective immobilization purposes by eliminating its three glutamic acid residues (S3E3) or substituting them with alanine (S3E3A), led to remaining only one carboxyl group at the C-terminal of peptides, higher LPS binding affinities and constant low cytotoxicity properties compared to S3 parent peptide. Both of newly designed variants also had one thiol group close to their C terminals.[19] In the current investigation, these particular carboxyl and thiol groups of S3E3 and S3E3A variants were exploited for chemo-selective immobilization of these variants on Sepharose resins via amide or thioether bonds, respectively. Then, LPS removal proficiencies of four constructed matrices were tested at different experimental conditions. The effects of matrices characteristics (the type of peptides and chemical groups of peptides and resins involved in immobilization reactions) and sample criteria (pH, NaCl, EDTA, and LPS concentration) on LPS removal efficiency (LRE) and protein recovery (R) of matrices were evaluated by using Plackett-Burman design method.