Biochemistry Essentials: Protein Folding, Hemoglobin, and Glycan Structure
Protein Structure and Function Fundamentals
Proteins are at the center of all biological processes. They catalyze reactions, regulate pathways, transport molecules, and form most of the structural framework of cells.
Core Principle: Structure → Function.
Historical Milestones in Protein Science
- Hsien Wu (1931): Showed that denaturation destroys non-covalent interactions, leading to unfolding and loss of function.
- Bernal & Hodgkin (1934): X-ray diffraction of pepsin revealed that proteins are ordered,
The Core Biomolecules: Carbohydrates, Proteins, and More
Carbohydrates
Definition
Optically active polyhydroxy aldehydes or ketones, or compounds that yield these upon hydrolysis.
General Formula and Name Origin
General Formula: Cₓ(H₂O)ᵧ
Name Origin: The name comes from “carbo” (meaning carbon) and “hydrate” (meaning water).
Classification of Carbohydrates
| Type | Definition | Examples |
|---|---|---|
| Monosaccharides | Cannot be hydrolyzed further into simpler units. | Glucose, Fructose, Ribose |
| Oligosaccharides | Yield 2–10 monosaccharide units upon hydrolysis. | Disaccharides: Sucrose, |
Cellular Metabolism: Energy, Lipid Synthesis, and Gene Regulation
Fatty Acid Oxidation
Fatty acids carry more energy per carbon because they are more reduced. They also carry less water along because they are nonpolar. In contrast, glucose and glycogen are for short-term energy needs and quick delivery, with fat stored in adipose tissue.
Lipids are transported in the blood as chylomicrons. Unsaturated fatty acids have a bent structure.
Glycerol Activation
- Glycerol kinase activates glycerol at the expense of ATP.
- Subsequent reactions recover more than enough ATP to
Human Metabolism Essentials: Pathways & Disorders
Carbohydrate Metabolism Fundamentals
Glycolysis: Key Outputs
- Products: 2 Pyruvate, 2 ATP, 2 NADH
Carbohydrate Classification
- Monosaccharides: Glucose, Fructose, Galactose
- Disaccharides:
- Lactose (Glucose + Galactose)
- Sucrose (Glucose + Fructose)
- Polysaccharides: Glycogen, Starch
Glycosylation vs. Glycation
- Glycosylation: Enzymes add carbohydrates to proteins.
- Glycation: Non-enzymatic attachment of glucose to proteins (e.g., HbA1c = glycated hemoglobin).
Blood Glucose Regulation
- Low Blood Glucose: Glucagon activates
Glycogen Metabolism: Synthesis and Breakdown
Glycogen Metabolism: Synthesis and Breakdown
Glycogen, the storage form of glucose, is a branched polymer crucial for energy regulation in the body. Both glycogen and starch store glucose for future metabolic needs. In animals, glycogen provides a rapidly accessible source of glucose, especially for tissues like the brain and red blood cells, which heavily rely on glucose as their primary energy source. While other tissues can utilize fatty acids or amino acids for energy, a constant supply of glucose
Glycolysis and Enzyme Kinetics: Metabolic Pathways Explained
Enzyme Kinetics Fundamentals
Key equations in enzyme kinetics:
- Kcat = Vmax / [E]t
- V0 = Vmax[S] / (αKM + [S])
Enzyme Inhibition Types
KI: Dissociation constant for the inhibitor from the enzyme.
Competitive Inhibitors
- Affects the slope of the Lineweaver-Burk plot.
- Y-intercept (1/Vmax) does not change.
- Apparent KM increases (when inhibitor concentration is high, the slope gets steeper and the line moves closer to the origin).
Uncompetitive Inhibitors
- Apparent KM changes.
- Vmax changes.
- Results in parallel lines