1. Hemoglobin is a multisubunit allosteric protein that carries 02 in erythrocyte. 1.1 Hemoglobin is a well-studied and well-understood protein. 1.1.1 It was one of the first proteins to have its molecular mass accurately determined. 1.1.2 The first protein to be characterized by ultracentrifuge. 1.1.3 The first protein to be associated with a specific physiological function

1. General studies of the peptide bond 1.1 The peptide(O=C-N-H) bond was found to be shorter than the C-N bond in a simple amine and atoms attached are coplanar. 1.1.1 This was revealed by X-ray diffraction studies of amino acids and of simple dipeptides and tripeptides. 1.1.2 The peptide (amide) bond was found to be about 1.32 A (C-N single bond, 1.49; C= double bond, 1.27), thus having partial double bond feature (should be rigid and unable to rotate freely)

Chapter Amino Acids, Peptides, and Proteins 0. General Introduction Proteins are polymers(多聚体) of amino acids. -20 amino acids(氨基酸)→ millions of proteins with different properties and activities. Protein structures are studied at primary, secondary, tertiary and quaternary levels. -a helix, B sheets, globular, complexes, denaturation and folding. Proteins have widely diverse forms and functions

1. Enzymes were among the first biological macromolecules to be studied chemically 1.1 Much of the early history of biochemistry is the history of enzyme research. 1.1.1 Biological catalysts were first recognized in studying animal food digestion and sugar fermentation with yeast (brewing and wine making)

1. Early studies on the peptide(protein) structure 1.1 The peptide(o=c-n-h) bond was found to be shorter than the C-N bond in a simple amine and atoms attached are coplanar. 1.1.1 This was revealed by X-ray diffraction studies of amino acids and of simple dipeptides and tripeptides

Assay:化验,分析,测定。 Enzyme activity: unit() is defined as the amount of enzyme which convert 1 micromole (umol) of substrate to product(s) in 1 minute under specified conditions. Specific activity: enzyme activity expressed per unit mass of protein present. (units/mg)

1. Carbohydrates are aldehyde or ketone compounds with multiple hydroxyl groups or substances that can yield such compounds on hydrolysis(p. 293) 1.1 Carbohydrates are the most abundant biomolecules on earth and have multiple roles in all forms of life. 1.1.1 Carbohydrates serve as energy stores (e.g., starch in plants, glycogen in animals), fuels (e.g., glucose), and metabolic intermediates (e.., ATP, many coenzymes)

1. Hemoglobin is a multisubunit allosteric rotein that carries 02 in erythrocyte. 1.1 Hemoglobin is a well-studied and well-understood protein. 1.1.1 It was one of the first proteins to have its molecular mass accurately determined. 1.1.2 The first protein to be characterized by ultracentrifuge. 1.1.3 The first protein to be associated with a specific physiological function

1. The nucleic acids, deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), are polymers of nucleotide units 1.1 DNA consists of four kinds of deoxyribonucleotide units linked together through covalent bonds 1.1.1 Each nucleotide unit is made of a nitrogenous base (the various part in the four different deoxyribonucleotides), a pentose sugar and a phosphate group

1. Lipids encompass a large and diverse group of organic compounds 1.1 Lipids are broadly defined as biological molecules that are soluble in organic solvents. 1.1.1 Lipids are usually extracted from biological materials by nonpolar solvents like ether, chloroform(氯仿), benzene(苯). 1.2 The biological functions of lipids are diverse. 1.2.1 Certain lipids(e.g., triacylglycerols(三脂酰甘油), commonly called fats) serve as efficient reserves for the storage of energy