DNA strands run parallel but in opposite directions. Nucleic acids have 5' and 3' ends. DNA replication occurs in leading and lagging strands. Hydrogen bonding between base pairs is essential
First myosin (M2) discovered by Wilhelm Kühne in 1864 from skeletal muscle. Myosins are ATP-dependent motor proteins responsible for muscle contraction. No single "myosin" exists, but a large superfamily of genes. Structure and function conserved across species
Glycoproteins contain covalently attached oligosaccharide chains to protein side-chains. Most common types are N-linked (asparagine) and O-linked (serine/threonine). Carbohydrate composition ranges from 1% to 70% of total protein mass
Membrane proteins are common and important, comprising about 30% of human proteins. Integral proteins are permanent membrane components, while peripheral proteins are temporary. Integral proteins can be transmembrane or monotopic, while peripheral proteins are non-covalent. Proteins can be modified with fatty acids, diacylglycerol, prenyl chains, or GPI
PDB files are textual descriptions of 3D molecular structures in Protein Data Bank. Contains atomic coordinates, secondary structure assignments, and experimental metadata. Can be saved as ENT or BRK extensions. Now considered legacy format, replaced by newer mmCIF format
SCOP classifies proteins based on structural and evolutionary relationships. Main levels include families, superfamilies, folds, IUPRs, classes and protein types. Each node has a unique seven-digit identifier. Database builds on representative protein domains from PDB and UniProtKB