Jul 27, 1976

pH dependence of the hydrolysis of hippuric acid esters by carboxypeptidase A

J W Bunting, S S Chu


The pH dependence (pH 4.5-10.5) of the hydrolysis of seven hippuric acid esters (C6H5CONHCH2C-O2CR1R2CO2H: 1a: R1 = R2 = H; 1b: R1 = R2 = CH3; 1c: R1 = H, R2 = p-ClC6H4; 1d: R1 = H, R2 = C2H5; 1e: R1 = H, R2 = (CH3)2CHCH2; 1f: R1 = H, R2 = C6H5; 1g: R1 = H, R2 = C6H5CH2) by bovine carboxypeptidase A has been investigated, and the pH dependence of the substrate activation of 1a-c and the substrate inhibition of 1d-g have been compared. For all seven esters the catalytically productive binding of the first substrate molecule depends on enzymatic pKa values of 6.0 and 9.1. For 1d, 1e, and 1g the rate of hydrolysis (k2app) of this complex is pH independent, whereas for 1f k2app depends on a pKa of 5.9. The rate of hydrolysis (k3app) of the 1:2 enzyme-substrate complex (ES2) is pH independent for 1d-g, but for 1a-c k3app depends on the following pKa values: 1a, 6.1 and 9.1; 1b, 5.4; 1c, 6.6. The pH dependences of k2app for 1f and k3app for 1c are rationalized by the presence of catalytically nonproductive species. Equivalent ES2 species are believed to be productive for 1c-g; however, the productive ES2 species for 1b must be quite different.

  • References10
  • Citations11

Mentioned in this Paper

Carboxypeptidase A
Bos taurus
Hippuricum acidum, hippuric acid, Homeopathic preparation
Carboxypeptidase A Activity
Plasma Protein Binding Capacity
Metabolic Inhibition

Trending Feeds


Coronaviruses encompass a large family of viruses that cause the common cold as well as more serious diseases, such as the ongoing outbreak of coronavirus disease 2019 (COVID-19; formally known as 2019-nCoV). Coronaviruses can spread from animals to humans; symptoms include fever, cough, shortness of breath, and breathing difficulties; in more severe cases, infection can lead to death. This feed covers recent research on COVID-19.

Bone Marrow Neoplasms

Bone Marrow Neoplasms are cancers that occur in the bone marrow. Discover the latest research on Bone Marrow Neoplasms here.

IGA Glomerulonephritis

IgA glomerulonephritis is a chronic form of glomerulonephritis characterized by deposits of predominantly Iimmunoglobin A in the mesangial area. Discover the latest research on IgA glomerulonephritis here.

Cryogenic Electron Microscopy

Cryogenic electron microscopy (Cryo-EM) allows the determination of biological macromolecules and their assemblies at a near-atomic resolution. Here is the latest research.

STING Receptor Agonists

Stimulator of IFN genes (STING) are a group of transmembrane proteins that are involved in the induction of type I interferon that is important in the innate immune response. The stimulation of STING has been an active area of research in the treatment of cancer and infectious diseases. Here is the latest research on STING receptor agonists.

LRRK2 & Immunity During Infection

Mutations in the LRRK2 gene are a risk-factor for developing Parkinson’s disease. However, LRRK2 has been shown to function as a central regulator of vesicular trafficking, infection, immunity, and inflammation. Here is the latest research on the role of this kinase on immunity during infection.

Antiphospholipid Syndrome

Antiphospholipid syndrome or antiphospholipid antibody syndrome (APS or APLS), is an autoimmune, hypercoagulable state caused by the presence of antibodies directed against phospholipids.

Meningococcal Myelitis

Meningococcal myelitis is characterized by inflammation and myelin damage to the meninges and spinal cord. Discover the latest research on meningococcal myelitis here.

Alzheimer's Disease: MS4A

Variants within membrane-spanning 4-domains subfamily A (MS4A) gene cluster have recently been implicated in Alzheimer's disease by recent genome-wide association studies. Here is the latest research.