Final answer:
Insulin is a polypeptide with a molecular weight of 5734 Da, comprising two amino acid chains, A and B, connected by disulfide bonds. The various classes of insulin, including lispro, NPH, aspart, detemir, regular, and glargine, represent modifications to insulin's molecular structure affecting onset, peak, and duration of action. These differences are used to manage blood sugar levels in diabetic patients with varying needs.
Step-by-step explanation:
Classes of Insulin: Lispro, NPH, Aspart, Detemir, Regular, Glargine:
Insulin is a polypeptide and a protein hormone synthesized in the pancreas, specifically by the Islets of Langerhans cells. Different types of insulin are designed to treat diabetes by replacing or supplementing the body's own insulin, which helps control blood sugar levels. Given its molecular structure, insulin consists of an A chain with 21 amino acids and a B chain with 30 amino acids, connected by disulfide bonds. The forms of insulin—lispro, NPH, aspart, detemir, regular and glargine—vary in onset and duration of action, which results from modifications in the insulin molecule or formulation that affect its pharmacokinetics. Insulin therapy is categorized based on the onset, peak and duration of the insulin's action. Regular insulin is also known as 'Short-Acting Insulin' and has a relatively quick onset but does not last as long as some other forms. NPH (Neutral Protamine Hagedorn), is an 'Intermediate-Acting Insulin' with a slower onset and longer duration of action due to the addition of protamine which slows down its absorption.
Lispro and aspart are 'Rapid-Acting Insulins' that begin working within minutes of injection and are closer mimics of the body's natural insulin release. Glargine and detemir are 'Long-Acting Insulins' that provide a steady amount of insulin over a longer period. The process of forming active insulin involves the synthesis of preproinsulin which is converted into proinsulin by the removal of amino acids from the N-terminal end. Proinsulin contains a 'C' chain that is cleaved off to form active insulin. The tertiary structure of insulin emphasizes its reactive capability, with disulfide bridges playing an important role in maintaining stability and functionality.