生化名词解释

asymmetric transcription：1) Only one strand of a gene can serve as template, the other which is complimentary to the template strand can’t be transcripted.
2) Not all the template strands of genes are found in the same strand on DNA molecule.
PI: The pH at which an amino acid has no net charge in solution is termed its isoelectric point, pI.
Peptide bond :a covalent bone between the α-amino group of one amino acid and the α-carboxyl group of another which is formed by removal of water from the α-carboxyl group of one amino acid and the α- amino group of another amino acid.
A peptide is a compound consisting of amino acids joined together by peptide bonds (or amide linkage )
Motif :Among various proteins, some special arrangements of several secondary structure elements are found, which are termed structural motifs.
Domain:Some polypeptide chains with secondary structures can fold into multiple compact semi-independent regions being connected by a flexible segment of polypeptide chain. These compact globular units are called domains.
Active center (active site ) :The active site of an enzyme is the region of the enzyme that can binds the substrate, to form an enzyme-substrate complex, and transforms it into product.
双重效应：Temperature affects the rate of enzyme-catalyzed reactions in two ways.
1：A rise in temperature increases the thermal energy of the substrate molecules (at less than 40 ℃).
2：At higher temperature( >50℃), enzymes are more easily denatured.
The optimum Temperature：The temperature of reaction at point which enzyme possesses maximal efficiency
Optimum pH：The pH at which an enzyme has maximal activity in solution. Transcription:the process which RNA polymerase catalyzes the yield of RNA with the one of double strands of DNA as template, NTPs as precursors, in the light of the rule of complementary base pairing
genetic code :The genetic code is the set of rules that specify how the nucleotide sequence of an mRNA is translated into the amino acid sequence of a polypeptide.
Codons :Each amino acid, Starting and ending genetic code in a protein is represented by three consecutive bases in mRNA, and these three-base combination, or triplets, are called codons.
Lipolysis: also named fat mobilization, is a process breaking down the fat (TAG) stored in adipose tissue and liberating the glycerol and FFAs from which into the blood circulation. Optimum pH：The pH at which an enzyme has maximal activity in solution.
Zymogen :Several enzymes are synthesized as larger inactive precursor forms called proenzymes or zymogens.
Isoenzymes:Multiple forms of an enzyme that can catalyze the same reaction but differ from each other in their amino acid sequences, substrate affinity, Vm, and /or regulatory properties are called isoenzymes (or isozymes )
The Characters of enzyme catalysis
(1) High effectively catalytic rate
(2) Highly specificity
(3) Reaction enzyme-catalyzed can be regulated.
Regulation of Enzyme Activity:Allosteric Regulation ;Covalent Modification;
Protein three-dimensional structure
primary structure: The linear sequence of amino acids in a protein molecule.The main chemical bonds are peptide bonds
secondary structure:the regular folding of regions of the polypeptide chain.The main chemical bonds: hydrogen bonds
•α -helix
•β-pleated sheet
•β-turn
•random coil
tertiary structure:spatial relationship among all amino acids in a polypeptide; it is the complete three-dimensional structure of the polypeptide.
Hydrophobic interactions ;electrostatic interaction ;salt bonds
multiple Van der Waals bonds ;hydrogen bonds
quaternary structure
Purification of Protein:Salt out ;Organic solvent precipitation ;
Adjusting pH to pI ;Changing the temperature of protein solution。