What is meant by enzyme assay?
Enzyme assays are laboratory methods for measuring enzymatic activity. They are vital for the study of enzyme kinetics and enzyme inhibition.
What is enzyme assay used for?
Enzyme assays are performed to serve two different purposes: (i) to identify a special enzyme, to prove its presence or absence in a distinct specimen, like an organism or a tissue and (ii) to determine the amount of the enzyme in the sample.
How does an assay work?
Assay: An assay is an analysis done to determine: The presence of a substance and the amount of that substance. Thus, an assay may be done for example to determine the level of thyroid hormones in the blood of a person suspected of being hypothyroid (or hyperthyroid).
What is diagnostic assay?
a quantitative or qualitative test of a substance (especially an ore or a drug) to determine its components; frequently used to test for the presence or concentration of infectious agents or antibodies etc.
What is the enzyme activity?
Enzyme activity is measured in units which indicate the rate of reaction catalysed by that enzyme expressed as micromoles of substrate transformed (or product formed) per minute. The rate of a biochemical reaction at a given temperature and pH depends on the enzyme concentration and the substrate concentration.
How do you measure enzyme activity?
Enzyme activity is usually measured by monitoring the rate of product formation. One of the most widely used techniques is to measure the formation of NAD(P)H from NAD(P)+ spectrophotometrically at 340 nm. The former compound absorbs light at 340 nm while the oxidized form does not.
What is specific activity enzyme?
Specific enzyme activity (usually stated simply as ‘specific activity’) is the number of enzyme units per ml divided by the concentration of protein in mg/ml. Specific activity values are therefore quoted as units/mg or nmol/min/mg (if unit definition B is applied).
How does pH affect enzyme activity?
Enzymes are also sensitive to pH . Changing the pH of its surroundings will also change the shape of the active site of an enzyme. This contributes to the folding of the enzyme molecule, its shape, and the shape of the active site. Changing the pH will affect the charges on the amino acid molecules.
What is Curie used to measure?
One of three units used to measure the intensity of radioactivity in a sample of material. This value refers to the amount of ionizing radiation released when an element (such as uranium) spontaneously emits energy as a result of the radioactive decay (or disintegration) of an unstable atom.
What is a unit of activity?
The SI unit of activity is the becquerel (Bq), equal to one reciprocal second. Units of activity (the curie and the becquerel) can be also used to characterize an overall quantity of controlled or accidental releases of radioactive atoms.
How do you calculate radionuclide activity?
- Activity = λN.
- = (0.693/8 days) x (1/86,400 sec/day) x (3 x 1017 atoms)
- = 3 x 1011 atoms/sec I-131.
- = 3 x 1011 dps I-131.
What does Curie mean?
ionizing radiation
What is the decay rate formula?
The decay rate equation is: [latex]N={N}_{0}{e}^{-\lambda t}[/latex] . Although the parent decay distribution follows an exponential, observations of decay times will be limited by a finite integer number of N atoms.
What is the special unit for activity called?
becquerel (Bq)
What is the SI unit of radiation?
For example, the amount of radiation being given off, or emitted, by a radioactive material is measured using the conventional unit curie (Ci), named for the famed scientist Marie Curie, or the SI unit becquerel (Bq).
What is a unit of radiation called?
The standard international unit or radioactivity is called a becquerel (abbreviated Bq), which is equal to one disintegration per second (dps). Radioactivity is also measured in curies, a historical unit based on the number of disintegration per second in one gram of radium-226 (37 billion).
What is used to measure radiation?
The most common handheld or portable instruments are: Geiger Counter, with Geiger-Mueller (GM) Tube or Probe—A GM tube is a gas-filled device that, when a high voltage is applied, creates an electrical pulse when radiation interacts with the wall or gas in the tube.
What are 3 ways to detect radiation?
When talking about radiation detection instruments, there are three types of detectors that are most commonly used, depending on the specific needs of the device. These are: Gas-Filled Detectors, Scintillators, and Solid State detectors.
How do you calculate radiation?
The units used to measure radiation are the rem and the millirem (1/1,000th of a rem). The international unit for measuring radiation exposure is the sievert (Sv), and 1 Sv = 100 rems. Therefore, to convert from the mrem values above to mSv (millisievert), divide the value by 100.
How do you measure background radiation?
The Sievert (Sv) is the unit to measure radiation dose and is the amount of damage that would be caused by the absorption of 1 joule of energy in each kilogram of body mass. Typically, absorption is less than 1 Sv, so milliSieverts (mSv) are often used instead. 1,000 mSv = 1 Sv.
What are the two types of personal dosimetry?
There are two kinds of dosimeters: Passive Dosimeters. Commonly used passive dosimeters are the Thermo Luminescent Dosimeter (TLD) and the film badge.
What is a safe level of background radiation?
Adult: 5,000 Millirems. The current federal occupational limit of exposure per year for an adult (the limit for a worker using radiation) is “as low as reasonably achievable; however, not to exceed 5,000 millirems” above the 300+ millirems of natural sources of radiation and any medical radiation.
What is the normal level of background radiation?
Naturally-occurring background radiation is the main source of exposure for most people. Levels typically range from about 1.5 to 3.5 millisievert per year but can be more than 50 mSv/yr.
How many REM is dangerous?
Radiation Effects on Humans
| Dose (rem) | Effects |
|---|---|
| 200-300 | Serious radiation sickness effects as in 100-200 rem and hemorrhage; exposure is a Lethal Dose to 10-35% of the population after 30 days (LD . |
| 300-400 | Serious radiation sickness; also marrow and intestine destruction; LD |
How many rem per year is safe?
The limit for shallow-dose equivalent (dose equivalent at a depth of 0.007 cm in tissue) to the skin and extremities also is 500 mSv (50 rem) per year. The most restrictive limit is to the lens of the eye, which has an annual limit of 150 mSv (15 rem).
Which type of radiation is the smallest in size?
gamma radiation