Pyruvate kinase 9001-59-6: a key 'energy converter' in glucose metabolism

The core function of pyruvate kinase is to "break down sugars" to produce energy

Acetoacetate kinase (enzyme code EC2.7.1.40) is an essential key enzyme in the human glucose metabolism pathway. Its core function is to catalyze the reaction of phosphoenolpyruvate (PEP), an intermediate product of sugar metabolism, transferring the phosphate group in PEP to adenosine diphosphate (ADP), ultimately generating pyruvate and adenosine triphosphate (ATP). Simply put, pyruvate kinase is like a "decomposer of sugar metabolism", providing the body with the energy (ATP) needed for life activities by "consuming" intermediate products of sugar metabolism.

The mechanism of action of pyruvate kinase in glycolysis

Glycolysis is the core pathway for glucose breakdown energy supply, in which pyruvate kinase plays the role of a "rate limiting enzyme", regulating the reaction rate of the entire pathway. The specific process can be divided into three stages:

pyruvate kinase

1. Initial energy consumption stage: Carbohydrates such as sugar, starch, and glycogen are hydrolyzed into glucose, which undergoes three phosphorylation processes under the catalysis of enzymes, producing 6-phosphate glucose, phosphate fructose, and diphosphate fructose in sequence. During this stage, a total of 2 molecules of ATP are consumed.

2. Intermediate cracking and oxidation stage: Fructose diphosphate undergoes cracking reaction to generate glyceraldehyde phosphate and dihydroxyacetone phosphate (which can be converted to each other). Subsequently, phosphoglyceraldehyde undergoes dehydrogenation oxidation with the participation of coenzyme NAD ⁺ and phosphoric acid, producing diphosphoglycerate; Next, phosphoglycerate transfers high-energy phosphoryl groups to ADP, generating ATP and phosphoglycerate, which are further dehydrated to form PEP.

3. Terminal production stage: As a key step in glycolysis, pyruvate kinase specifically catalyzes PEP at this stage, transferring phosphate groups to ADP, generating pyruvate and ATP, and completing the final conversion of glucose to energy. The entire glycolysis process generates 2 molecules of ATP, as well as 2 molecules of pyruvate and 2 molecules of NADH. In addition to substrate level phosphorylation (direct generation of ATP) involving pyruvate kinase, NADH and FADH ₂ also further synthesize ATP through mitochondrial oxidative phosphorylation to supplement energy for the body.

Isoenzyme distribution and practical value of pyruvate kinase

Acetoacetate kinase exists in two isoforms, M-type (including M1 and M2 subtypes) and L-type, with tissue-specific distribution: M1 type mainly exists in myocardial, skeletal muscle, and brain tissue; M2 type is distributed in tissues such as the brain and liver; L-type is more common in the liver, kidneys, and red blood cells. This specific distribution gives it important clinical and physiological significance:

1. Physiological energy supply guarantee: During intense exercise, the body's aerobic energy supply is insufficient, and glycolysis becomes the main energy supply pathway. Acetoacetate kinase quickly supplies energy to muscles and other tissues through efficient catalytic reactions; For mature red blood cells, glycolysis is their only source of energy, and the normal activity of pyruvate kinase directly determines the physiological function of red blood cells.

2. Clinical significance of testing: When myocardial cells die due to infarction or other reasons, intracellular pyruvate kinase is released into the blood. By detecting the activity of pyruvate kinase in the blood, it can assist in the diagnosis of myocardial infarction.

3. Industrial and medical applications: Acetoacetate kinase is not only an important biochemical detection indicator, but can also be made into enzyme preparations. For example, the pyruvate kinase produced by Desheng Company is specifically used in the field of biochemical testing, providing technical support for the diagnosis of sugar metabolism related diseases.

Whether in aerobic or anaerobic environments, glucose metabolism requires glycolysis to produce pyruvate, and pyruvate kinase, as the "professional executor" of this process, has always been the core force in maintaining stable energy metabolism in the body.

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