Biomedical Engineering Reference
In-Depth Information
6 Radioactive Labeling
Many of radioactive isotopes are very useful for the following bio-
chemical processes (Table 6.1). The radioactive label is introduced
into macromolecules, especially proteins, either during biosynthe-
sis, e.g., during translation in the presence of
35
S-methionine, or
enzymatically, e.g., by use of
32
P-labeled ATP during protein phos-
phorylation by protein kinases, or chemically by modification of
amino acid side chains. Examples for reagents used in chemical
radiolabeling of proteins are given in Table 6.2.
The main advantages of radioisotopes are the simple and very
sensitive detection of the labels as well as the fact that labeled
groups are chemically identical to their naturally occurring ana-
logues; thus, macromolecules may be monitored within their natu-
ral environment and without significant loss of material. But even at
low doses radioactive isotopes are dangerous, especially when they
are incorporated into biologically active molecules. Protection and
disposal are the main disadvantages; therefore, non-radioactive
labeling, such as biotinylation or fluorescent labeling, should be
preferred whenever it is possible (examples given in Protocol 3.6.7
and Protocol 4.1.10, respectively).
Important!
Take whatever actions are necessary to ensure that
you comply with the national or state regulations governing the
use of radioactive materials! Follow the code of good laboratory
practice inaddition to specific precautions relating to the particular
radionuclides used. Laboratory overalls, safety glasses, and surgical
glovesmustbewornatalltimes.Avoidradioactivepollutionofyour
bench to avoid endangering of your surroundings.
Working with radioactivity is not more dangerous than working
Golden rules for
handling radio-
active materials
with infectious or poisonous material, especially if “ten golden
rules”
1
are observed: 1. Understand the nature of the hazard and
get practical training. 2. Plan ahead to minimize time spent han-
dling radioactivity. 3. Distance yourself appropriately from sources
of radiation. 4. Use appropriate shielding for the type of radia-
tion. 5. Contain radioactive materials within defined work areas. 6.
Wear appropriate protective clothing and dosimeters. 7. Monitor
the work area frequently for contamination. 8. Follow the local rules
1
Amersham Biosciences (2002) “Safe and secure - a guide to working
safely with radiolabeled compounds”
