What is urease activity?

Urease is an enzyme that hydrolyses urea (carbamide) into ammonia and carbon dioxide and is produced by several bacterial species. Urease activity in the plaque in situ has been measured indirectly by quantifying the amount of ammonia formed using Nessler’s reagent [9,10,11].

How is urease activity measured?

The current published method for measuring urease activity in phytoplankton involves measuring the hydrolysis of urea into ammonium. The method was previously optimized for studies of phytoplankton cultures, not for nat- ural assemblages of phytoplankton.

Is urease found in soil?

Urease is widely distributed in soils and was one of the first soil enzymes to be experimentally evaluated (Conrad, 1940).

Is urease an extracellular enzyme?

Among the extracellular enzymes related with nitrogen (N), urease (urea amidohydrolase, EC 3.5. 1.5) is responsible for the breakdown of urea. Urease has an important role in the occurrence of accessibility of N for plant growth in N cycle and in the widespread usage of urea as a fertilizer.

What is urease used for?

Urease is a virulence factor found in various pathogenic bacteria. It is essential in colonization of a host organism and in maintenance of bacterial cells in tissues. Due to its enzymatic activity, urease has a toxic effect on human cells.

Does urease increase pH?

Urease activity increases the pH of its environment as ammonia is produced, which is basic.

What is the substrate of the urease test?

The presence of urease is detectable when the organisms are grown in a urea broth medium containing the pH indicator phenol red. As the substrate urea is split into its products, the presence of ammonia creates an alkaline environment that causes the phenol red to turn to deep pink.

What is dehydrogenase activity in soil?

Soil dehydrogenases (EC 1.1. 1.) are the major representatives of the Oxidoreductase enzymes class (Gu et al., 2009). Dehydrogenases play a significant role in the biological oxidation of soil organic matter (OM) by transferring hydrogen from organic substrates to inorganic acceptors (Zhang et al., 2010).

What does a negative urease test mean?

Rapid urease tests are fast, inexpensive, and easy to perform. A limitation is that this method requires a high density of bacteria in the specimen. Negative results could mean that the level of bacteria in the specimen obtained is low.

What does a positive urease test mean?

The urease test identifies those organisms that are capable of hydrolyzing urea to produce ammonia and carbon dioxide. It is primarily used to distinguish urease-positive Proteeae from other Enterobacteriaceae.

When would you use the urease test?

This test is used to identify bacteria capable of hydrolyzing urea using the enzyme urease. It is commonly used to distinguish the genus Proteus from other enteric bacteria. The hydrolysis of urea forms the weak base, ammonia, as one of its products.

How is the oxidation rate of amidohydrolase measured?

Hans Ulrich Bergmeyer, in Methods of Enzymatic Analysis (Second Edition), Volume 4, 1974 The oxidation of NADH, as measured by the decrease of extinction at 340 (334, 365) nm, is directly proportional to the amount of creatinine present.

Is there a second amidohydrolase in the body?

A second amidohydrolase, N -acylethanolamine-hydrolyzing acid amidase (NAAA), has been identified in peripheral tissues ( Ueda, Yamanaka, & Yamamoto, 2001 ). NAAA is present in lysosomes, active at acidic pH, and prefers PEA as a substrate over AEA.

What causes an extinction change in amidohydrolase assay?

Interference in the assay: Ammonium ions cause an extinction change which is independent of the urease activity, and which starts before the addition of urea. Large amounts of ammonia can be removed by dialysis, traces (< 0.8 µ mole/3 ml.) can be removed by preliminary incubation with excess NADH.

What is the systematic name of acylamide amidohydrolase?

This enzyme belongs to the family of hydrolases, those acting on carbon-nitrogen bonds other than peptide bonds, specifically in linear amides. The systematic name of this enzyme class is acylamide amidohydrolase. Other names in common use include acylamidase, acylase, amidohydrolase, deaminase, fatty acylamidase, and N-acetylaminohydrolase.