Biochemistry Enzymes Overview

A reaction whose rate is constant and independent of substrate concentration, but directly proportional to enzyme concentration

A substance that competes with the substrate for the enzyme's active site, leading to reversible inhibition.

A substance that inhibits an enzyme by binding to a site other than the active site (allosteric site).

A method of measuring enzyme activity by determining the concentration of indicator substance at several time intervals.

A substance that binds to the enzyme-substrate complex, increasing inhibition as substrate concentration increases.

Measuring enzyme activity by continuously monitoring concentration changes over time.

A method to measure enzyme activity by linking it to a colorimetric reaction.

The standard unit for expressing enzymatic activity.

An enzyme involved in cleaving phosphate containing compounds in alkaline environments, facilitating substance movement across cell membranes.

Facilitates the movement of substances across cell membranes by cleaving phosphate-containing compounds.

Elevated levels are commonly linked to liver and bone diseases.

The normal range is 30-90 U/L.

Elevated ALP levels may indicate osteoblastic tumors (bone cancer), cancers in various locations (lung, breast, ovarian, gynecological, etc.)

A type of ALP found in certain cancers (lung, breast, ovarian, gynecological) and is heat-stable.

A type of ALP linked to pancreatic and bile duct cancers.

Low ALP levels are seen in conditions like hypophosphatasia (insufficient bone calcification), malnutrition, and certain medical procedures.

Different forms of the same enzyme with slightly different structures and properties, often found in different tissues.

An enzyme that catalyzes the transfer of an amino group between aspartate and α-ketoacids, producing oxaloacetate and glutamate.

Acid Phosphatase, an enzyme that is particularly important in the diagnosis of prostate cancer.

The prostatic isoenzyme, which is inhibited by tartrate.

Possible sexual assault. ACP persists in vaginal swabs for several hours to days after semen exposure.

A type of AST (Aspartate Aminotransferase) enzyme primarily found in the mitochondria of cells, especially in heart tissue, liver, and skeletal muscle.

An isoenzyme of alkaline phosphatase (ACP) primarily found in bone tissue. It's used in bone metabolism and is resistant to inhibition by tartrate.

Elevated levels of AST in the blood can indicate damage to tissues rich in this enzyme, such as the heart, liver, and skeletal muscles.

A heart attack, where the heart muscle is damaged due to a lack of blood flow. This leads to increased levels of AST, often 4-10 times the normal range.

An enzyme involved in energy storage and transfer in muscles, especially during muscle contraction. CK helps convert creatine phosphate to ATP for energy.

During muscle activity, CK uses creatine phosphate to create ATP for muscle energy. This allows sustained muscle contraction.

When muscles are resting, CK converts ATP back to creatine phosphate, storing energy for future muscle activity.

Another aminotransferase enzyme, similar to AST, with high concentration in the liver. It's used in the evaluation of liver damage.

Gamma-Glutamyl Transferase (GGT) is an enzyme found in various parts of the body, particularly in the liver. It is a key player in the transfer of glutamyl groups from peptides to other molecules.

Elevated GGT levels often signify liver damage. The liver is a major source of GGT release into the bloodstream.

GGT is a highly sensitive indicator of excessive alcohol consumption, even in cases of 'occult' (hidden) alcoholism.

Creatine Kinase-MB (CK-MB) is an enzyme that rises rapidly in the blood after a heart attack (AMI). Its levels peak within 12-24 hours and decline within 48-72 hours.

CK-MB levels remain normal in cases of angina, which is chest pain caused by temporary lack of blood flow to the heart.

Duchenne Muscular Dystrophy (DMD) is a genetic disorder that causes progressive muscle weakness. It is characterized by extremely elevated GGT levels.

Normal GGT levels vary slightly between men and women. For men, the range is 6-45 units per liter (U/L), while for women it is 5-30 U/L.

Smoking can increase GGT levels. Heavy smokers have higher GGT levels compared to moderate smokers or non-smokers.

Increased bilirubin levels due to blockage of bile flow from the liver.

Impaired bile flow within the liver itself.

An enzyme that converts angiotensin I to angiotensin II, a powerful vasoconstrictor.

Elevated ACE levels are often seen in sarcoidosis, a chronic inflammatory disease.

Enzymes that break down acetylcholine, a neurotransmitter.

A rare condition where the body lacks the enzyme pseudocholinesterase, leading to prolonged apnea after succinylcholine.

An enzyme primarily found in the liver, useful for diagnosing liver disease.

Levels of liver enzymes like ALP and OCT can indicate liver health.