Resources » Technical Resource Centers » Gene Technical Resources » Nucleic Acids and Protein Calculations Spectrophotometric Conversions
** This web page provides several useful tables of common biological constants and conversions. These include metric prefixes, spectrophotometiric conversions, agarose/polyacrylamide gel resolutions, etc. You can use these tables to aid your DNA/RNA/protein quantification, electrophoresis gel preparation, protein synthesis and other research activities.
Prefix | Symbol | Factor |
---|---|---|
kilo | k | 103 |
centi | c | 10-2 |
milli | m | 10-3 |
micro | µ | 10-6 |
nano | n | 10-9 |
pico | p | 10-12 |
femto | f | 10-15 |
atto | a | 10-18 |
zepto | z | 10-21 |
1 A260 unit of double-stranded DNA=50 µg/ml |
1 A260 unit of single-stranded DNA=33 µg/ml |
1 A260 unit of single-stranded RNA=40 µg/ml |
1 µg of 1,000 bp DNA |
≈
|
1.52 pmol(3.03 pmol of ends) |
1 µg of pBR322 DNA |
≈
|
0.36 pmol DNA |
1 pmol of 1,000 bp DNA |
≈
|
0.66 µg |
1 pmol of pBR322 DNA |
≈
|
2.8 µg |
Note:
pBR322DNA:(4,361 bp)
For dsDNA |
---|
To convert pmol to µg: |
pmol × N × 660 pg/pmol × 1 µg/106 pg = µg |
To convert µg to pmol: |
µg × 106 pg/1 µg × pmol/660 pg × 1/N = pmol |
For ssDNA |
To convert pmol to µg: |
pmol × N × 330 pg/pmol × 1µg/106 pg = µg |
To convert µg to pmol: |
µg × 106 pg/1 µg × pmol/330 pg × 1/N = pmol |
where N is the number of nucleotides and 330 pg/pmol is the average MW of a nucleotide |
100 pmol of 100 kDa protein |
=
|
10 µg |
100 pmol of 50 kDa protein |
=
|
5 µg |
100 pmol of 10 kDa protein |
=
|
1 µg |
100 pmol of 1 kDa protein |
=
|
100 ng |
1 kb DNA |
→
|
333 amino acids |
→
|
37 kDa protein | |
270 b DNA |
→
|
10 kDa protein |
810 b DNA |
→
|
30 kDa protein |
1.35 kb DNA |
→
|
50 kDa protein |
2.7 kb DNA |
→
|
100 kDa protein |
average MW of an amino acid |
≈
|
110 daltons |
Dalton (Da) is an alternate name for the atomic mass unit, and kilodalton (kDa) is 1,000 daltons. Thus a protein with a mass of 64 kDa has a molecular weight of 64,000 grams per mole |
Recommended % Agarose | Optimum Resolution for Linear DNA (Size of fragments in nucleotides;bp) |
---|---|
0.5 | 1,000-30,000 |
0.7 | 800-12,000 |
1.0 | 500-10,000 |
1.2 | 400-7,000 |
1.5 | 200-3,000 |
2.0 | 50-2,000 |
Recommended % Acrylamide | Protein Size Range |
---|---|
8 | 40-200 kDa |
10 | 21-100 kDa |
12 | 10-40 kDa |
Nucleic Acid | Number of Nucleotides | Molecular Weight |
---|---|---|
lambda DNA | 48,502(dsDNA) | 3.2 × 107 |
pBR322DNA | 4,361(dsDNA) | 2.8 × 106 |
28S rRNA | 4,800 | 1.6 × 106 |
23S rRNA(E.coli) | 2,900 | 1.0 × 106 |
18S rRNA | 1,900 | 6.5 × 105 |
16S rRNA(E.coli) | 1,500 | 5.1 × 105 |
5S rRNA(E.coli) | 120 | 4.1 × 104 |
tRNA(E.coli) | 75 | 2.5 × 104 |
*Molecular weights based on actual sequence. |
1. Average MW of dsDNA base pair = 600. |
2. Average MW of ssDNA base =330. |
3. Average MW of RNA base =340. |