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IPRS, Inc.
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There are a number of methods available for measuring levels of Magnesium in samples. One challenge is to determine levels without interference from other ions, since normally samples are mixtures of many ions. The second and even greater challenge is to measure the amount of Mg that is free and available to participate in biochemical reactions. Most methods give total Mg. It has been only recently that an Ion Selective Electrode (ISE) has become available that will measure the free Mg++. This method however, while fine for body fluids that can be extracted (line blood or urine), it cannot be used on the cellular level. Some scientists have developed colorimetric tests. The following material is extracted from a draft document on cation selectivity and measurements. A number of compounds are known to have a high affinity for various cations including for calcium, magnesium, manganese and zinc. There are a variety of proteins that have special binding sites for metal ions but they have their own unique set of characteristics. The present study is directed to compounds other than proteins, compounds that typically are of much smaller size than metal-binding proteins. Among these are EDTA and EGTA that have acidic carboxyl groups and negatively polarized nitrogen atoms to which cations may be attracted. Others have oxygen from hydroxyl or phosphate groups (for example pyrophosphate, orthophosphate, ATP/ADP, etc.). Still others are compounds not prevalent in biological systems as indicated in the following list and elaborated upon in the text and tables below: * 4-oxo-4H-quinolizine-3-carboxylates reported by Otten et al. * 1,5-bis(2-hydroxyphenyl)-3-cyanoformazans cited in Kodak patents 4753890 and 5215925* ortho-cresolphthalein complexones * Arsenazo III-based methods * Calmagite (3-hydroxy-4-[(2-hydroxy-5-methylphenyl)azo]-1-naphthalenesulfonic acid)
* Eriochrome Black T
(3-hydroxy-4-[(1-hydroxy-2-naphthalenyl)azo]-7-nitro-1-naphthalene These latter compounds have various functional groups to which metal ions bind (including sulfonic). In some instances the binding brings about a change in light absorption or a change in fluorescence that can be measured. Other techniques include use of radioactive isotopes. Radioactive isotopes are available for other ions - Ca, Na, K for membrane flux studies and binding. However the radioactive isotope for Mg is fairly short lived and requires special neutron activation in a nuclear reactor.
Measurements of Other Cations Ion Selective Electrodes are available for H+, Na+, K+, and Ca++ and many years of research has been carried out using such techniques. Spectrophotometric procedures are also well developed and used frequently in laboratory and clinical practice. Measurements of Enzymes Spectrophotometric procedures are also well developed and used frequently in laboratory and clinical practice. Measurements of Metabolites Problem of multi-factor screening is sensitivity. GC/MS can measure metabolic intermediates for high output reactions but cannot determine levels in the microgram or nanogram levels at which hormones and many enzymes occur. Genomic Research Techniques Spectrophotometric procedures are also well developed and used frequently in laboratory and clinical practice. HPLC, GC/MS, immunofluroescence, Electrophoresis, Western blot, northern blot, etc. High Throughput Systems for GWAS et al. Accelyrs and other manufactures of automated equipment and associated software and reference databases. Bio-informatics With high throughput screen techniques a massive amount of data is produced. Some of the top researchers talk in terms of terrabytes of data. This requires powerful computers if not super-computers and/or parallel distributed computing by networked computers. Super-computer applications are also being used for analysis of protein folding, 3D structure prediction, and other computational challenges like comparing protein or gene sequences looking for homologies or defects. See Software Tools for further details on these topics. References ------------------------------------------------- This page is under development. Links to major topics only are live. -------------------------------------------------
© 2012 IPRS Inc.
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Basic Research
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