This document discusses insulin, including its structure, synthesis, regulation, effects, and analytical methods. It notes that insulin is a peptide hormone produced in the pancreas that regulates carbohydrate, fat, and protein metabolism. Insulin has two polypeptide chains and is encoded by the INS gene. High or low insulin levels can cause diseases like insulinoma tumors or diabetes. Common analytical methods to detect insulin include immunoassays and chromatography.

1. INSULIN: STRUCTURE, SYNTHESIS AND ANALYTICAL
METHODS
Prepared By :- SHADY ALHUSSAYNI
SBCB (R1)

2. OUTLINE:
• Insulin structure, synthesis and regulation.
• Biochemical and physiological effects of Insulin.
• Review of analytical methods.
• Associated diseases at variety level of insulin.

3. INTRODUCTION:
-It is a peptide hormone produced by beta cells of Langerhans of pancreas.
-It is the main anabolic hormone of the body.
-It regulates the metabolism of carbohydrates, fats and protein by promoting the
absorption of glucose from the blood into fat in liver and skeletal muscle cells.

4. INTRODUCTION:
-It was the first hormone to be isolated, purified & synthesized.
-First hormone to be sequenced.
-First hormone to be produced by recombinant DNA technology.

5. STRUCTURE:
• Human Insulin contain 51 aminoacids, arranged in TWO Polypeptide chains.
• Chain A = 21 AA
• Chain B = 30 AA
• Two Interchain Disulfide bridge = A7-B7 & A20-B19.
• Intrachain Disulfide link in chain A = 6-11.

6. STRUCTURE:

7. SYNTHESIS AND REGULATION:
• The preproinsulin precursor of insulin is encoded by the INS gene.
• Gene is located on Chr 11.
• Produced from β-cell of Langerhans of pancreas.
• Synthesis involve two precursors :-
1. Preproinsulin = 108AA
2. Proinsulin = 86 AA

8. SYNTHESIS AND REGULATION:
• These are serially degraded to form the active hormone Insulin and
Connecting peptide (C-Peptide).
• C-peptide has no biological activity, however its estimation in plasma
serves as the useful index for endogenous production of insulin.
• In β-cells, Insulin combines with Zinc to form a complex & stored in
granules.

9. REGULATION OF INSULIN SECRETION
• About 40-50Units secreted daily by Human pancreas.
• Normal value is = 20-30 μU/ml.

10. BIOCHEMICAL AND PHYSIOLOGICAL EFFECTS:
(1) Carbohydrate metabolism:
(a) It increases the rate of transport of glucose across the cell membrane
in adipose tissue and muscle.
(b) it increases the rate of glycolysis in muscle and adipose tissue.
(c) it stimulates the rate of glycogen synthesis in several tissues. It also decreases the rate of
glycogen breakdown in muscle and liver.
(d) it inhibits the rate of gluconeogenesis in the liver.

11. (2) Lipid Metabolism:
(a) It decreases the rate of lipolysis in adipose tissue and hence lowers the plasma fatty
acid level
(b) it stimulates fatty acid and triacylglycerol synthesis in tissues.
(c) it increases the rate of very-low-density lipoprotein formation in the liver.
(d) it increases the uptake of triglyceride from the blood into adipose tissue and muscle.
(e) it decreases the rate of fatty acid oxidation in muscle and liver
(f) it increases the rate of cholesterol synthesis in liver.

12. (3) Protein Metabolism:
(a) It increases the rate of transport of some amino acids into tissues,
(b) it increases the rate of protein synthesis in muscle, adipose tissue, liver, and other
tissues.
(c) it decreases the rate of protein degradation in muscle (and perhaps other tissues)
(d) it decreases the rate of urea formation.

14. Review of Analytical Methods.
• Nowadays, immunoassays and chromatographic assays are the primary methods that
have been developed for insulin analysis.
• Generally, immunoassays including:
• Enzyme-linked immunosorbent assay (ELISA).
• Chemiluminescence immunoassay (CLIA).
• Radioimmunoassay (RIA).
((good selectivity towards insulin with less interferences))

15. Review of Analytical Methods.
• Chromatographic assays including:
• High performance liquid chromatography coupled with ultraviolet detection (HPLC-UV).
• Liquid chromatography with tandem mass spectrometry (LC-MS/MS).
((are highly sensitive and capable of simultaneous detection of insulin)).

16. VARIATION IN THE LEVEL OF INSULIN SECRETION AND
ASSOCIATED DISEASES
• High level of insulin:
1-Acromegaly
2-Cushing syndrome
3-Fructose or galactose intolerance
4-Insulinomas – a tumor of beta cells producing excess insulin.
5-Obesity
6-Insulin resistance, such as appears in type 2 diabetes and metabolic syndrome

17. VARIATION INTHE LEVEL OF INSULIN SECRETION AND
ASSOCIATED DISEASES
• Low level of insulin:
1-Diabetes
2-Hypopituitarism
3-Pancreatic diseases such as chronic pancreatitis (including cystic fibrosis) and pancreatic
cancer.

18. DISEASE ASSOCIATEDWITH HIGH INSULIN LEVEL
• Insulinoma :- Insulinoma is a tumor found in the pancreas that continues to
produce insulin even when your blood sugar drops too low.
• High blood insulin levels cause low blood sugar levels called Hypoglycemia.
• Hypoglycemia may be mild, leading to symptoms such as anxiety and hunger or it
can be severe, leading to seizures, coma and even death.

19. SYMPTOMS OF INSULINOMA
• Anxiety
• Weight Gain (patient can
become excessively obese)
• Behavior Changes
• CloudedVision
• Confusion
• Hunger
• Loss of Consciousness
• Rapid Heart Rate
• Sweating

20. TESTS FOR INSULINOMA DIAGNOSIS
• After fasting, blood tested for:
• C-peptide level.
• Glucose level.
• Insulin level.
• Drugs that cause the pancreas to release insulin.
• CT or MRI scan of the abdomen may be done to look for a tumor in the pancreas.

21. DISEASE ASSOCIATEDWITH LOW INSULIN LEVEL
• Diabetes mellitus (DM):-
• Commonly known as diabetes, is a group of metabolic disorders characterized by high blood
sugar levels over a prolonged period. Diabetes is due to either the pancreas not producing
enough insulin, or the cells of the body not responding properly to the insulin produced.
• Type 1 diabetes results from the pancreas's failure to produce enough insulin due to loss of
beta cells.This form was previously referred to as "insulin-dependent diabetes mellitus"
• Type 2 diabetes begins with insulin resistance, a condition in which cells fail to respond to
insulin properly.As the disease progresses, a lack of insulin may also develop.This form was
previously referred to as "non-insulin-dependent diabetes mellitus"

22. SYMPTOMS
OF DIABETES

23. DIAGNOSIS OF DIABETES
• Analysis for the Diagnosis & Monitoring of the Diabetes status:-
• Blood Glucose (Fasting & PPBS).
• OGTT (Oral Glucose tolerance test).
• Glycated Hb (HbA1c).
• Urine Glucose.
• Insulin, C-Peptide.

24. INSULIN RESISTANCE (IR)
• Insulin resistance (IR) is a pathological condition in which cells fail to
respond normally to the insulin.
• Tests For insulin resistance:-
• Hyperinsulinemic euglycemic clamp (Gold std).
• Modified insulin suppression test.
• HOMA (homeostatic model assessment), QUICKI (quantitative insulin
sensitivity check index).

25. THANK YOU