Enzimichean agus Structar Enzim

Enzymes

• Enzymes are biological catalysts that speed up the rate of biochemical reactions.
• Most enzymes are 3-D globular proteins.
• Some special RNA molecules also act as enzymes, called ribozymes.

Enzyme Structure

• Active site: A region that binds substrates, cofactors, and prosthetic groups. It contains residues that help hold the substrate in place. This shape is determined by the tertiary structure of the protein.
• The active site is divided into two parts:
  • Binding site: This part of the active site recognizes and binds the substrate.
  • Catalytic site: This part of the active site performs the catalytic action of the enzyme.
• Cofactors: Non-protein molecules that carry out chemical reactions that cannot be performed by the standard 20 amino acids; they activate the protein.
• Apoenzyme: an enzyme without its cofactor.
• Holoenzyme: a complete enzyme comprising the apoenzyme and its cofactor.

Cofactors

• Inorganic cofactors: Inorganic molecules needed for proper enzyme activity.
• Example: Magnesium (Mg) is a cofactor for hexokinase.
• Organic cofactors: Organic molecules needed for proper enzyme activity.
  • Prosthetic groups: Tightly bound organic cofactors.
  • Examples: Flavins, heme groups, biotins.
  • Coenzymes: Loosely bound organic cofactors.
  • Examples: NAD+, FAD.

Enzyme substrates

• Substrates: Reactants in a biochemical reaction.
• Binding of a substrate to an enzyme forms an enzyme-substrate complex.

Enzyme kinetics

• Enzyme kinetics: The branch of study that examines the rate of enzyme-catalysed reactions.

Enzyme Activity Factors

• Temperature: Affects the rates of enzyme catalysed reactions.
• pH: Affects the rates of enzyme catalysed reactions.
• Substrate concentration: Affects the rates of enzyme catalysed reactions.

Enzyme Inhibition

• Inhibition: Prevention of enzyme activity via interactions with inhibitors.
• Reversible inhibition: Inhibitors can bind and unbind from the enzyme.
  • Competitive inhibition: Inhibitors compete with the substrate for the active site.
  • Non-competitive inhibition: Inhibitors bind to a site other than the active site (allosteric site).
  • Mixed inhibition: Inhibitors can bind to either the enzyme or the enzyme-substrate complex.
• Irreversible inhibition: Inhibitors bind to an enzyme permanently, halting its activity.
• Examples: Aspirin, which targets and covalently modifies a key enzyme involved in inflammation.

Activation

• Activation: Conversion of inactive enzyme form to active form.
• Cofactors: Enzymes can be activated by cofactors which are non-protein molecules that assist in aiding certain reactions.
• Zymogen Activation: Inactive enzyme precursors are activated via proteolytic cleavage.

Enzyme Specificity

• Bond specificity: Enzymes act on substrates with a similar structure and containing a particular bond type.
• Group Specificity: Enzymes are specific to the structure surrounding the substrate.
• Substrate Specificity: Enzymes only act on a particular substrate.
• Optical/Stereo-specificity: Enzymes exhibit specificity towards an optical configuration.
• Dual Specificity: Enzymes act on a single substrate through two different types of reactions.

Lipids,

• Lipids are diverse groups of chemical compounds including fats and oils.
• They are hydrophobic and some are amphipathic (possessing both polar and non-polar parts).

Carbohydrates

• Carbohydrates are polyhydroxyaldehydes or polyhydroxyketones that yield simpler sugars upon hydrolysis.
• Carbohydrates have general formula: C_n(H₂O)_n.
• There are three main classes of carbohydrates:
  • Monosaccharides: Simplest carbohydrates that cannot be hydrolysed.
    • Aldoses: Contain aldehyde groups.
    • Ketoses: Contain ketone groups.
  • Disaccharides: Two monosaccharides linked by glycosidic bond.
  • Polysaccharides: Multiple monosaccharides linked together.
  • Examples: Glucose, fructose, sucrose, cellulose.

Nucleic Acids

• Nucleic acids are biopolymers containing monomer units:
  • Bases (purines and pyrimidines)
  • Monosaccharides (pentoses)
  • Phosphate Groups
• The primary structure of a nucleic acid is the sequence of bases.
• Secondary structure involves the 3-dimensional conformation of the polynucleotide backbone.
• Tertiary structures pertain to the interactions between DNA and proteins.

Ceistean mu innleachdan enzim agus an structar aca. Faigh a-mach mar a tha enzimichean ag obair, na h-eileamaidean a bhiodh a' toirt taic dhaibh, agus an diofar dhleastanasan a tha annta. Cuiridh iad fiosrachadh mu na h-eilthirean agus an obair a tha iad a' dhèanamh.