Protein long-chain

The above metastable foams are produced from surfactant solutions near or above the critical micelle concentration (c.m.c.). The stability is governed by the balance of surface forces (see below). Film thickness is comparable to the range of intermolecular forces. In the absence of external disturbances, these foams may stay stable indefinitely They are produced using proteins, long-chain fatty acids or solid particles. 

High-stability (metastable) foams are prepared from detergents, proteins, long-chain fatty acids (near or above the critical micelle concentration (CMC)), particles, etc. These foams usually have a lifetime up... 

Analysis and prediction of side-chain conformation have long been predicated on statistical analysis of data from protein structures. Early rotamer libraries [91-93] ignored backbone conformation and instead gave the proportions of side-chain rotamers for each of the 18 amino acids with side-chain dihedral degrees of freedom. In recent years, it has become possible to take account of the effect of the backbone conformation on the distribution of side-chain rotamers [28,94-96]. McGregor et al. [94] and Schrauber et al. [97] produced rotamer libraries based on secondary structure. Dunbrack and Karplus [95] instead examined the variation in rotamer distributions as a function of the backbone dihedrals ( ) and V /, later providing conformational analysis to justify this choice [96]. Dunbrack and Cohen [28] extended the analysis of protein side-chain conformation by using Bayesian statistics to derive the full backbone-dependent rotamer libraries at all... 

A continuous lipidic cubic phase is obtained by mixing a long-chain lipid such as monoolein with a small amount of water. The result is a highly viscous state where the lipids are packed in curved continuous bilayers extending in three dimensions and which are interpenetrated by communicating aqueous channels. Crystallization of incorporated proteins starts inside the lipid phase and growth is achieved by lateral diffusion of the protein molecules to the nucleation sites. This system has recently been used to obtain three-dimensional crystals 20 x 20 x 8 pm in size of the membrane protein bacteriorhodopsin, which diffracted to 2 A resolution using a microfocus beam at the European Synchrotron Radiation Facility. 

Fibrous proteins can serve as structural materials for the same reason that other polymers do they are long-chain molecules. By cross-linking, interleaving and intertwining the proper combination of individual long-chain molecules, bulk properties are obtained that can serve many different functions. Fibrous proteins are usually divided in three different groups dependent on the secondary structure of the individual molecules coiled-coil a helices present in keratin and myosin, the triple helix in collagen, and P sheets in amyloid fibers and silks. 

Fibrous proteins are long-chain polymers that are used as structural materials. Most contain specific repetitive amino acid sequences and fall into one of three groups coiled-coil a helices as in keratin and myosin triple helices as in collagen and p sheets as in silk and amyloid fibrils. 

Long-chain polyisoprenoid. molecules with a terminal alcohol moiety are called, polyprenols. The dolichols, one class of polyprenols (Figure 8.18), consist of 16 to 22 isoprene units and, in the form of dolichyl phosphates, function to carry carbohydrate units in the biosynthesis of glycoproteins in animals. Polyprenyl groups serve to anchor certain proteins to biological membranes (discussed in Chapter 9). 

Their value as building blocks to make proteins stems from the fact that amino acids can join together into long chains by Forming amide bonds between the -NH2 of one amino acid and the -C02H of another. For classification purposes, chains with fewer than 50 amino acids are often called peptides, while the term protein is used for larger chains. 

Just as proteins are biopolymers made of amino acids, nucleic acids are biopolv-mers made of nucleotides joined together to form a long chain. Each nucleotide is composed of a nucleoside bonded to a phosphate group, and each nucleoside is composed of an aldopentose sugar linked through its anomeric carbon to the nitrogen atom of a heterocyclic purine or pyrimidine base. 

When you consider how many different ways thirty (or even fewer) different amino acids can be combined in long chains of a hundred or more, you can see why there are so many proteins known, and why different living species of... 

In Section 18-6.3 the composition of proteins was given. They are large, amide-linked polymers of amino acids. However, the long chain formula (Figure 18-14, p. 348) does not represent all that is known about the structure of proteins. It shows the covalent structure properly but does not indicate the relative positions of the atoms in space. 

The hindering potentials must be of importance in the question of the flexibility of long-chain molecules such as synthetic polymers and naturally occurring macromolecules such as proteins and nucleic acids. Again, direct information on barriers in these molecules will be difficult to obtain but inferences can presumably be drawn from experiments on simpler analogues. 

Fatty acid transport protein paralogues 1-6 FATP 1-6 Gene symbols SLC27A1-6 Solute carrier family 27A Very long-chain acyl-CoA synthetase VLCS... 

Fatty acid transport proteins (FATPs) are an evolutionary conserved family of integral membrane proteins found at the plasma membrane and on internal membranes. FATPs facilitate the unidirectional uptake and/ or intracellular activation of unesterified long-chain and very long-chain fatty acids (LCFAs) into a variety of lipid-metabolizing cells and tissues. 

This precipitation process can be carried out rather cleverly on the surface of a reverse phase. If the protein solution is brought into contact with a reversed phase, and the protein has dispersive groups that allow dispersive interactions with the bonded phase, a layer of protein will be adsorbed onto the surface. This is similar to the adsorption of a long chain alcohol on the surface of a reverse phase according to the Langmuir Adsorption Isotherm which has been discussed in an earlier chapter. Now the surface will be covered by a relatively small amount of protein. If, however, the salt concentration is now increased, then the protein already on the surface acts as deposition or seeding sites for the rest of the protein. Removal of the reverse phase will separate the protein from the bulk matrix and the original protein can be recovered from the reverse phase by a separate procedure. 

The Condensation of Long-chain Fatty Acids with Polysaccharides and Proteins, A. S. Jones, M. A. G. Kaye, and M. Stacey, J. Chem. Soc., (1952) 5016-5020. 

Schemes are available, however, that start from the free carboxylic acid, plus an activator . Dicyclohexylcarbodiimide, DCC, has been extensively employed as a promoter in esterification reactions, and in protein chemistry for peptide bond formation [187]. Although the reagent is toxic, and a stoichiometric concentration or more is necessary, this procedure is very useful, especially when a new derivative is targeted. The reaction usually proceeds at room temperature, is not subject to steric hindrance, and the conditions are mild, so that several types of functional groups can be employed, including acid-sensitive unsaturated acyl groups. In combination with 4-pyrrolidinonepyridine, this reagent has been employed for the preparation of long-chain fatty esters of cellulose from carboxylic acids, as depicted in Fig. 5 [166,185,188] ...

Enzymes 7,9, and 13 form a trifunctional protein associated with the inner face of the inner mitochondrial membrane. Very-long-chain acyl-CoA dehydrogenase is also associated with other inner mitochondrial membranes while the other enzymes are in the matrix and may be loosely associated with the inner face of the inner membrane. A medium-chain 2-enoyl-CoA hydratase may also be present in the mitochondrial matrix. 

The free fatty acid uptake by tissues is related directly to the plasma free fatty acid concentration, which in turn is determined by the rate of lipolysis in adipose tissue. After dissociation of the fatty acid-albumin complex at the plasma membrane, fatty acids bind to a membrane tty acid transport protein that acts as a transmembrane cotransporter with Na. On entering the cytosol, free fatty acids are bound by intracellular fatty acid-binding proteins. The role of these proteins in intracellular transport is thought to be similar to that of serum albumin in extracellular transport of long-chain fatty acids. 

Interest in import of proteins into peroxisomes has been stimulated by studies on Zellweger syndrome. This condition is apparent at birth and is characterized by profound neurologic impairment, victims often dying within a year. The number of peroxisomes can vary from being almost normal to being virtually absent in some patients. Biochemical findings include an accumulation of very long chain fatty acids, abnormalities of... 

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