Govt Exams
HbA1c is formed through non-enzymatic glycation of hemoglobin by glucose, reflecting average blood glucose over 2-3 months (RBC lifespan). Normal HbA1c <5.7%, diagnostic for diabetes ≥6.5%.
The anomeric carbon (C1 in glucose) is the carbon that becomes chiral when the open-chain form cyclizes to form the hemiacetal. This is the site of α/β isomerism.
Pyruvate carboxylase catalyzes the first committed step of gluconeogenesis, converting pyruvate to oxaloacetate. Lactate is converted to pyruvate by LDH, then to glucose via gluconeogenesis.
Glycogen branching enzyme transfers segments of 6-7 glucose residues from the outer chains to create α(1→6) branch points, increasing solubility and accessibility for glycogen phosphorylase.
Aldose reductase catalyzes the reduction of glucose to sorbitol using NADPH. Sorbitol dehydrogenase catalyzes the oxidation of sorbitol to fructose in the second step of the polyol pathway.
The Maillard reaction is a non-enzymatic browning reaction between carbonyl groups of reducing sugars and amino groups of proteins/amino acids, producing AGEs. This is significant in glycemic control and diabetes complications.
Non-competitive inhibition decreases Vmax while keeping Km constant. This occurs when an inhibitor binds to a site other than the active site (allosteric site), preventing product formation regardless of substrate concentration. The Km value remains unchanged because substrate binding affinity is unaffected.
Disulfide bonds are formed in oxidizing environments. The rough endoplasmic reticulum (RER) and Golgi apparatus maintain oxidizing conditions suitable for disulfide bond formation, unlike the reducing environment of the cytoplasm. The enzyme protein disulfide isomerase (PDI) facilitates this process in the ER lumen.
Enteropeptidase (enterokinase), secreted by the duodenal mucosa, cleaves a specific peptide bond in trypsinogen to produce active trypsin, initiating the cascade of pancreatic protease activation.
Above optimal temperature, increased thermal energy disrupts hydrogen bonds and hydrophobic interactions maintaining the 3D structure, causing denaturation and loss of catalytic activity.