Amino acids in pneumolysin important for hemolytic activity identified by random mutagenesis

Amino acids are the monomers that comprise proteins. Each amino acid has the same fundamental structure, which consists of a central carbon atom, or the alpha (α) carbon, bonded to an amino group (NH2), a carboxyl group (COOH), and to a hydrogen atom. Every amino acid also has another atom or group of atoms bonded to the central atom known as the R group. There are 20 common amino acids present in proteins, each with a different R group. Variation in the amino acid sequence is responsible for...

Mutations are changes in the sequence of DNA. These changes can occur spontaneously during DNA replication or be induced by environmental factors. Mutations can be characterized in several ways: by whether and how they alter the amino acid sequence of the protein, by the scale of the DNA affected, and by whether they affect somatic or germline cells.Consequences of Point Mutations at the Molecular LevelMutations that affect a single nucleotide are called point mutations. When point mutations...

Many proteins’ biological role depends on their interactions with their ligands, small molecules that bind to specific locations on the protein known as ligand-binding sites. Ligand-binding sites are often conserved among homologous proteins as these sites are critical for protein function.
Binding sites are often located in large pockets, and if their location on a protein’s surface is unknown, it can be predicted using various approaches. The energetic method computationally analyses the...

Proteins are chains of amino acids that are connected by peptide bonds and folded into a 3-dimensional structure. The side chains of individual amino acid residues determine the interactions among amino acid residues, and ultimately the folding of the protein. Depending on the length and structural complexity, chains of amino acid residues are classified as oligopeptides, polypeptides, or proteins.Amino Acid Residues Are the Building Blocks of ProteinsAn amino acid is a molecule that contains a...

Proteins are dynamic macromolecules that carry out a wide variety of essential processes; however, the activities of most proteins depend on their interactions with other molecules or ions, known as ligands.
Protein-ligand interactions are quite specific; even though numerous potential ligands surround a cellular protein at any given time, only a particular ligand can bind to that protein. Moreover, a ligand binds only to a dedicated area on the surface of the protein, known as the...

Proteins are polymers of amino acids linked together by peptide bonds. Proteins and polypeptides are interchangeably used to refer to long chains of amino acids. However, polypeptides have a molecular weight of fewer than 10,000 daltons, while proteins have greater molecular weight.  Polypeptides with less than 20 amino acids are called oligopeptides or simply peptides. Interactions among the constituent amino acid side chains of proteins help them fold into a stable 3-dimensional structure...