Proteins in Cosmetics
E. Desmond Goddard, James V. Gruber in Principles of Polymer Science and Technology in Cosmetics and Personal Care, 1999
The structure of natural proteins is organized on four possible levels. The primary structure is given by the covalent bonds (mainly —— and —SS—) linking different amino acids within the polypeptide chain; it is therefore determined by the amino acid sequence and the possible presence of cystine residues (cysteine-SS-cysteine). The secondary structure is characterized by the spatial location of adjacent amino acid side chains, which, by hydrogen bonds and other weak linkages, can give rise to formation of regular periodic structures like the α-helix of the collagen molecule or the β-pleated sheet of the silk fibroin. The tertiary structure is related to steric interaction and spatial location of nonadjacent amino acid side chains; this organization level allows the protein chain to resume a folded shape and locate the hydrophobic residues in the internal regions of the molecule, reducing the unfavorable interaction with water. The tertiary structure is characteristic of globular proteins. The quaternary organization is related to association and spatial arrangement of two or more polypeptide chains (subunits) cross-linked by hydrophobic and hydrogen bonds or disulfide bridges. Higher levels of structural organization (supersecondary structure, domains) have also been found and studied for their biological role and importance (11).
Genetics as a Tool to Understand Structure and Function
Peter M. Gresshoff in Molecular Biology of Symbiotic Nitrogen Fixation, 2018
X-ray crystallography then revealed that hemoglobin has a quaternary structure, consisting of four protein subunits of two chemical types (α and β), each closely resembling the myoglobin molecule, organized into a compact symmetry.9 Most large biological globular proteins are quaternary aggregates of polypeptide chains, each several hundred amino acids long. In some proteins the subunits are identical and usually specified by a single gene; in others they are different. For example, the E. coli β-galactosidase enzyme contains four identical polypeptide chains, tryptophan synthetase is composed of two pairs of dissimilar chains coded by different genes, while the Neurospora crassa glutamic dehydrogenase enzyme contains six to eight subunits. If such quaternary proteins are purified and the individual subunits separated by lowering the pH, at first they display negligible or no functional activity at normal pH, even when they are all identical, but activity gradually returns as aggregates reform. Thus, the formation of active enzymes is not coded for directly by the DNA, but by the structure of the individual subunits. Similarly, if the disulfide bonds of globular proteins are reduced and broken, the polypeptide chains become linear, but refold automatically into their tertiary structure when normal conditions are restored.
PEGylated Dendritic Nanoparticulate Carriers of Anti-Cancer Drugs
Mansoor M. Amiji in Nanotechnology for Cancer Therapy, 2006
Additionally, many other types of interesting, valuable, aesthetically pleasing dendritic systems have been developed such as Dendrophanes that were first described by Diederich and coworkers. They called these phenyl methane-based cyclophane. These were designed as globular proteins. Metallodendrimers include Ruthenium-terpyridine complexed dendrimers by Newkome and coworkers, dendritic iron (II) complexes by Chow and coworkers, zinc-porphyrin dendrimers by Diederich and coworkers, etc. and they contain metal complexed in dendrimer structure. Polyamino phosphine containing dendrimers are phosphorous containing dendrimers. Mesogen functionalized carbosilane dendrimer involves functionalization by 36 mesogenic units attached through C-5 spacer to liquid crystalline dendrimer that form smectic-A phase in a temperature range of 117–130°C. Dendritic box was based on construction of a chiral shell of protected amino acids onto polypropyleneimine dendrimers with 64 amino end groups. These monodispersed dendritic containers of nanometric dimensions have physically entrapped or locked in guest molecules (Jansen et al. 1994; Jansen and Meijer 1995). Toyokuni et al. (1994) described an example of carbohydrate dendrimers for tumor-associated carbohydrate antigens. They linked it without the use of macromolecular carrier or an adjuvant, and they conjugated it with starburst PAMAM dendrimers to elicit antibody responses.
Computational re-design of protein structures to improve solubility
Published in Expert Opinion on Drug Discovery, 2019
Susanna Navarro, Salvador Ventura
These sequence-based aggregation predictors perform accurately for proteins displaying extended or partially unfolded conformations, because their APRs are exposed to solvent. They have become powerful tools to study the aggregation determinants of pathogenic intrinsically disordered proteins such as Aβ42, α-synuclein, tau or amylin, allowing to evaluate the impact of genetic mutations on their aggregation rates. However, a new conceptual scenario is needed when dealing with globular proteins. The majority of these proteins bury sequential APRs into their hydrophobic core or engage them in the cooperative non-covalent interactions that sustain their secondary and tertiary structures, excluding them from undesired intermolecular contacts [61]. Thus, their APRs are irrelevant for the aggregation of natively folded states. In addition, in many cases, APRs can be exposed at the surface of globular proteins playing a functional role in protein-protein binding [62,63]. These APRs are often formed by non-consecutive residues arranged in structural proximity, not being effectively identified by the sequence-based algorithms.
Emerging PEGylated non-biologic drugs
Published in Expert Opinion on Emerging Drugs, 2019
Eun Ji Park, Jiyoung Choi, Kang Choon Lee, Dong Hee Na
PEGylation is a pharmaceutical technology that attaches one or more polyethylene glycol (PEG) molecules to therapeutic molecules, thereby improving their pharmaceutical properties [1]. PEG, a synthetic polymer comprised of repeating ethylene oxide units, is chemically inert and has low toxicity, and has been approved by Food and Drug Administration (FDA) for oral, intravenous, and dermal applications in the pharmaceutical industry [2]. The PEG is known to entangle two to three water molecules per ethylene oxide unit, which makes its hydrodynamic radius between 5 and 10 times larger than that of a globular protein of a similar molecular weight [3]. Owing to these properties of PEG, PEGylation affords the prolonged circulation lifetime owing to reduced renal clearance, improved stability against proteolytic enzymes, enhanced solubility in biological fluids, and reduced toxicity/immunogenicity [4]. Based on these effects, numerous PEGylated biomolecules have shown enhanced therapeutic efficacy and fewer undesirable effects compared with their unmodified forms [5].
Taenia solium proteins: a beautiful kaleidoscope of pro and anti-inflammatory antigens
Published in Expert Review of Proteomics, 2020
Naina Arora, Amit Prasad
The evolution of high throughput techniques are boon to biologists, specially to study complex extracellular parasites, which undergoes metamorphosis from egg to adult in several stages and in different hosts. The major limitations in studying cestodes have been the unavailability of good quality, reliable genomic and proteomic database. Tsai et. al., (2013) sequenced four adult tapeworms and revealed the host-dependent survival nature of these cestode parasites. Though the electronic annotation specifically to T. solium is still not available, but by using sequence alignment tools we attempted to gain knowledge about this parasite’s protein profile. It is a host-dependent parasite that’s why it lacks all-inclusive machinery for synthesis of biomolecules essential for survival and has a very complex proteome make-up with diverse functions [17,39]. The parasite protein’s VF and ESPs behave differently inside the host and carry out different functions which were substantiated from their shared, yet unique protein abundance pattern noticed in this study. The VF was having more globular protein (GRAVY below 0) than membrane-bound proteins. Globular proteins are water soluble in nature and are transported easily as compared to membrane-bound, which require complex machinery and have been found to be involved in binding, catalysis, transport, immunity, cellular metabolism, and many more. Thus, underlying the importance of VF proteins for survival of parasite.
Related Knowledge Centers
- Biochemistry
- Colloid
- Fibrous Protein
- Globin
- Intrinsically Disordered Proteins
- Membrane Protein
- Protein
- Protein Folding
- Protein Fold Class
- Structural Motif