Elements of Polymer Science
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
The shape of protein molecules is not given completely by their secondary structure. Sections of peptide chains may be linked chemically through sulfur bonds of cystein groups, as in the case of keratins, or by salt bridges between carboxyl groups and ammonium groups, such as the glutamic acid-lysine links present in α-keratin (59). This overall three-dimensional structure of a protein molecule is known as its tertiary structure. In addition to tertiary structure, a protein may exhibit a quaternary structure that originates from associations of several proteins or of proteins and nonprotein sustances. Rheology and Mechanical Properties of Polymers
Introduction to Cell Biology
Anthony R. Mundy, John M. Fitzpatrick, David E. Neal, Nicholas J. R. George in The Scientific Basis of Urology, 2010
Proteins are macromolecules comprising a chain of amino acids (Fig. 1A). There are 20 different amino acids that can be stringed together in any order by peptide bonds to make up an almost infinite number of proteins. Usually, proteins are of 100 to 1000 amino acids in length. The primary structure of a protein refers to its amino acid sequence. Once assembled, small sections of a protein will fold into a secondary structure stabilized by hydrogen bonding between neighboring or proximal amino acids. These secondary structures include a-helices, β-sheets, and turns, and a protein may contain many regions with different secondary structures that stabilize each other. The overall three-dimensional or tertiary structure of a protein in its entirety is determined by the intramolecular bonds between local and distant amino acids. These bonds are weaker than those maintaining secondary structure, and thus the tertiary structure can be manipulated or altered in certain conditions. This propensity for flexibility has allowed proteins to assume enumerable functional roles in the cell, as will be discussed later. Finally, a single protein, or monomer, can assemble with other monomers to form multimeric structures, and in many cases, multimeric assembly is required for protein function. This quaternary structure is defined by the number and relative order of protein monomers within a multimeric complex.
Gene Expression and Function of the Cellular Receptor for u-PA (u-PAR)
Pia Glas-Greenwalt in Fibrinolysis in Disease Molecular and Hemovascular Aspects of Fibrinolysis, 2019
The putative domain structure of u-PAR is further supported by the observation that each of the three repeating sequences is in turn homologous to a number of otherwise diverse proteins.28,35 These proteins are thought to constitute a protein superfamily and are typified by a group of murine leukocyte antigens known collectively as Ly-6, but also includes the murine thymocyte antigen ThB, the human complement component MIRL (membrane inhibitor of reactive lysis, CD59), and the squid brain glycoprotein Sgp-2. With the exception of the closely related Ly-6 sequences, the homology between these proteins is again essentially confined to the spacing pattern of the cysteine residues, suggesting a conserved folding configuration of these molecules, although all identified members are also GPI-anchored proteins. The secondary and tertiary structure of these proteins is unknown** but, in contrast to u-PAR, all consist of only a single domain.
Tracing protein and proteome history with chronologies and networks: folding recapitulates evolution
Published in Expert Review of Proteomics, 2021
Gustavo Caetano-Anollés, M. Fayez Aziz, Fizza Mughal, Derek Caetano-Anollés
At higher levels of organization, striking regularities exist in how secondary structures assemble into tightly packed layered arrangements of the polypeptide chain [54]. These regularities in connectivities and relative orientation of secondary structures (topologies and architectures, respectively), which result in part from physical and chemical properties that are intrinsic [55,56], are responsible for protein tertiary structure. Tertiary structure first manifests in the formation of autonomous folding elements known as protein structural domains (Figure 1A). Domains are structural [57], evolutionary [58] and functional [59] units of proteins, mainly because of their ‘compact globular’ folded structure [first observed by Phillips [60] in lysozyme], their high evolutionary conservation [61] and their recurrent association with molecular functions [62]. Since proteins often contain more than one domain, domains appear repeatedly, individually or combined with other domains sometimes in unusually complex arrangements [5]. This enhances domain recurrence. Tertiary structure also manifests in supradomains, domain combinations that behave as modules and appear recurrently in multidomain proteins [63].
Permeation-enhancing effects and mechanisms of O-acylterpineol on isosorbide dinitrate: mechanistic insights based on ATR-FTIR spectroscopy, molecular modeling, and CLSM images
Published in Drug Delivery, 2019
Yan Li, Chunyan Wang, Jian Wang, Tianzhe Chu, Linlin Zhao, Ligang Zhao
Comparing TER-C14 with control, the amide II bands shifted reproducibly by about 1.2 cm−1 to lower wavenumbers after application of TET-C4, the similar effect was also observed after application NMP. A previous literature report states that the observed amide II bands in SC at about 1540 and 1508 cm−1 can be attributed to α-helical conformation and β-pleated sheets, respectively (Lin et al., 1996). Recently, a lot of new insights about the protein structure have been proposed by Goormaghtigh’group (Grimard et al., 2004; Sarroukh et al., 2013; Baldassarre et al., 2015; De Meutter et al., 2017), who reported that the tertiary structure of protein also existed and could change in the absence of significant secondary structure modification. The changes could be monitored by kinetics of deuteration or polarized IR light.
Bioanalytical strategies in drug discovery and development
Published in Drug Metabolism Reviews, 2021
Aarzoo Thakur, Zhiyuan Tan, Tsubasa Kameyama, Eman El-Khateeb, Shakti Nagpal, Stephanie Malone, Rohitash Jamwal, Chukwunonso K. Nwabufo
During denaturation, secondary and tertiary structures of the protein are removed. This allows for better protonation as more sites are revealed. The denaturing process is done by adding either an alkali or an acid to the sample or by using high-temperature and surfactants. This step can be done in a couple of different ways. In-solution denaturing can be done with urea or thiourea, followed by disulfide reduction and adding alkali to the sample. Reduction and alkylation necessarily follow this process to prevent re-folding. In gel-denaturation is an alternative to in-solution denaturing. It involves protein separation through gel electrophoresis. At times, additional sample extraction procedures, such as SPE or MWCO filtration may also be needed before injecting onto an LC-MS/MS (DelGuidice et al. 2020).
Related Knowledge Centers
- Atom
- Peptide
- Protein
- Protein Domain
- Protein Quaternary Structure
- Protein Secondary Structure
- Amino Acid
- Side Chain
- Protein Structure
- Cyclol