Related Experiment Videos
Conidial alkaline phosphatase from Neurospora crassa
J C Say1, R P Furriel, P Ciancaglini
1Departamento de Química, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto-USP, Brazil.
Phytochemistry
|January 1, 1996
Summary
Researchers purified alkaline phosphatase from Neurospora crassa conidia. This enzyme, a tetramer with significant carbohydrate content, exhibits unique properties suggesting it is a distinct class of alkaline phosphatase in this organism.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Alkaline phosphatases (APs) are crucial enzymes involved in various biological processes.
- Neurospora crassa synthesizes multiple APs, including constitutive and phosphate-repressible forms.
- Characterization of APs from specific developmental stages, like conidia, is essential for understanding their roles.
Purpose of the Study:
- To purify and characterize the alkaline phosphatase present in Neurospora crassa conidia.
- To determine the enzyme's molecular properties, including subunit composition and isoelectric point.
- To investigate the effects of metal ions and substrate concentration on enzyme activity and specificity.
Main Methods:
- Purification of alkaline phosphatase from Neurospora crassa wild type conidia.
- Enzyme characterization using gel filtration and SDS-PAGE to determine molecular weight and subunit structure.
- Isoelectric focusing to determine the isoelectric point (pI).
- Enzyme activity assays under varying conditions (pH, substrate concentration, metal ions) and substrate specificity analysis.
Main Results:
- Purified conidial alkaline phosphatase has an estimated native molecular weight of 145,000 Da (with Mg2+) or 110,000 Da (without Mg2+).
- SDS-PAGE revealed a single subunit of 36,000 Da, indicating a tetrameric structure.
- The enzyme is acidic (pI = 4.0 +/- 0.1) and contains 40% carbohydrate.
- Enzyme activity and optimal pH were influenced by substrate concentration and magnesium ions; calcium ions showed inhibitory effects at higher concentrations.
- Substrate specificity analysis distinguished it from other known N. crassa APs.
Conclusions:
- The conidial alkaline phosphatase of Neurospora crassa is a distinct molecular entity.
- Its tetrameric structure, acidic nature, high carbohydrate content, and unique regulatory properties differentiate it from other APs in this organism.
- These findings suggest a specialized function for this conidial AP.