Amino acid sequences solubility point

If the macromolecule is very small and/or there are only a few crosslink points per chain, then the macromolecules forming such a cross-linked network are still soluble. In the enzyme ribonuclease, for example, the only chain, the main chain, is joined to itself by four disulfide bridges (Figure 2-6), whereas in insulin, another protein, there are two chains, the A and B chains, which are connected by two disulfide bridges. The A and B chains differ in the nature and sequence of their a-amino acids. 

Cytochrome c is, as we have pointed out, indispensable for aerobic life, therefore it has been on our planet in cellular organisms ever since that form of life emerged. Because the protein is relatively small and highly soluble, it has been possible to prepare it from various sources, to study its amino acid composition and sequence, and, finally, to describe its three-dimensional structure. 

Polynucleotides are biopolymers that carry genetic information involved in the processes of replication and protein synthesis (4). An essentially infinite number, n, of proteins can be made by assembling the 20 amino acids in various miax>structural combinations and sequence lengths. The 20 amino acids contain four major types of side chains, i.e., hydrophobic, hydrophilic, basic and acidic. Most polypeptides and proteins are water-soluble or water-swellable. The solubility of proteins varies considerably based on composition and condition of ionic strength, pH, and concentration. Those wifii die highest density of polar groups or electrolyte character are the most soluble. Therefore, solubility in water is lowest at the isoelectric point and increases with increasing basicity or acidity. 

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