Alcantara, Ria Diane R.

MT1335

General Properties and Definition of the follow enzymes:

I. MI Profile

1. Creatine Kinase (CK)

A. Definition - CK is an enzyme with a molecular weight of approximately 82,000 Da that is generally associated with ATP regeneration in contractile or transport systems. Its predominant physiologic function occurs in muscle cells, where it is involved in the storage of high-energy creatine phosphate.

B. Isoenzymes, Tissue Source & Associated Diseases

Isoenzyme Tissue Source Associated Diseases/ ConditionsCK-BB Brain

BladderLungProstateUterusColonStomachThyroid

Central nervous system shockAnoxic encephalopathyCerebrovascular accidentSeizurePlacental or uterine traumaCarcinomaReye’s syndromeMalignant hyperthermiaAcute and chronic renal failure

CK-MB HeartSkeletal Muscle

Myocardial infarctionMyocardial injuryInflammatory heart diseaseCardiac surgeryDuchenne-type muscular dystrophyReye’s syndrome

CK-MM HeartSkeletal Muscle

Myocardial infarctionSkeletal muscle disorderMuscular dystrophyMalignant hyperthermiaPhysical activityIntramuscular injection

2. Aspartate Amino Tranferase (AST)

A. Definition - Aspartate aminotransferase (AST) is an enzyme belonging to the class of transferases. It is commonly referred to as a transaminase and is involved in the transfer of an amino group between aspartate and α-keto acids. The older terminology, serum glutamic oxaloacetic transaminase (SGOT, or GOT), may also be used.

B. Associated Diseases – Myocardial infarction, Hepatic Disorder & Skeletal muscle disorder.

C. Tissue Source – AST is widely distributed in human tissue. The highest concentrations are found in cardiac tissue, liver, and skeletal muscle, with smaller amounts found in the kidney, pancreas, and erythrocytes.

3. Lactate Dehydrogenase (LDH)

A. Definition – LDH is an enzyme that catalyzes the interconversion of lactic and pyruvic acids. It is a hydrogen-transfer enzyme that uses the coenzyme NAD+.

B. Associated Diseases – Myocardial infarction, Hepatic disorder, Hemolysis & CarcinomaC. Tissue Source – LDH is widely distributed in the body. High activities are found in the

heart, liver, skeletal muscle, kidney, and erythrocytes; lesser amounts are found in the lung, smooth muscle, and brain.

II. Liver Enzymes

4. Alanine Amino Transferase (ALT)

A. Definition - Alanine aminotransferase (ALT) is a transferase with enzymatic activity similar to that of AST. Specifically, it catalyzes the transfer of an amino group from alanine to α-ketoglutarate with the formation of glutamate and pyruvate.

B. Associated Diseases – Hepatic disordersC. Tissue Source – ALT is distributed in many tissues, with comparatively high

concentrations in the liver. It is considered the more liver-specific enzyme of the transferases.

5. Alkaline Phosphatase (ALP)

A. Definition – ALP belongs to a group of enzymes that catalyze the hydrolysis of various phosphomonoesters at an alkaline pH. Consequently, ALP is a nonspecific enzyme capable of reacting with many different substrates. Specifically, ALP functions to liberate inorganic phosphate from an organic phosphate ester with the concomitant production of an alcohol.

B. Associated Diseases – Hepatic disorder & Bone disorder

C. Tissue Source – ALP activity is present on cell surfaces in most human tissue. The highest concentrations are found in the intestine, liver, bone, spleen, placenta, and kidney.

6. y-Glutamyl Transferase (GGT)

A. Definition – y-Glutamyltransferase (GGT) is an enzyme involved in the transfer of the y-glutamyl residue from y-glutamyl peptides to amino acids, H2O, and other small peptides. In most biologic systems, glutathione serves as the y-glutamyl donor.

B. Associated Diseases – Hepatic disorderC. Tissue Source – GGT activity is found primarily in tissues of the kidney, brain, prostate,

pancreas, and liver. Clinical applications of assay, however, are confined mainly to evaluation of liver and biliary system disorders.

III. Pancreatic Enzymes

7. Amylase (AMS)

A. Definition – Amylase (AMY) is an enzyme belonging to the class of hydrolases that catalyze the breakdown of starch and glycogen. Starch consists of both amylose and amylopectin.

B. Associated Diseases – Acute pancreatitisC. Tissue Source – The acinar cells of the pancreas and the salivary glands are the major

tissue sources of serum AMY. Lesser concentrations are found in skeletal muscle and the small intestine and fallopian tubes.

8. Lipase (LPS)

A. Definition – LPS is an enzyme that hydrolyzes the ester linkages of fats to produce alcohols and fatty acids. Specifically, LPS catalyzes the partial hydrolysis of dietary triglycerides in the intestine to the 2-monoglyceride intermediate, with the production of long-chain fatty acids.

B. Associated Diseases – Acute pancreatitisC. Tissue Source – LPS concentration is found primarily in the pancreas, although it is also

present in the stomach and small intestine.

IV. Other Enzymes

9. Acid Phosphatase (ACP)

A. Definition – Acid phosphatase (ACP) belongs to the same group of phosphatase enzymes as ALP and is a hydrolase that catalyzes the same type of reactions.

B. Associated Diseases – Prostatic carcinoma

C. Tissue Source – ACP activity is found in the prostate, bone, liver, spleen, kidney, erythrocytes, and platelets. The prostate is the richest source, with many times the activity found in other tissue.

10. Glucose-6-Phosphate Dehydrogenase (G-6-PDH)

A. Definition – G-6-PD is an oxidoreductase that catalyzes the oxidation of glucose-6-phosphate to 6-phosphogluconate or the corresponding lactone. The reaction is important as the first step in the pentose phosphate shunt of glucose metabolism with the ultimate production of NADPH.

B. Associated Diseases – Drug-induced hemolytic anemiaC. Tissue Source – Sources of G-6-PD include the adrenal cortex, spleen, thymus, lymph

nodes, lactating mammary gland, and erythrocytes. Little activity is found in normal serum.