關于核酸和蛋白的一些換算

一，Spectrophotometric Conversions
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

二，DNA Molar Conversions
1 µg of 1,000 bp DNA =1.52pmol(3.03pmol of ends)
1 µg of pBR322 DNA =0.36pmol DNA
1 pmol of 1,000 bp DNA =0.66 µg
1 pmol of pBR322 DNA =2.8 µg

三，Formulas for DNA Molar Conversions
1，For dsDNA
To convert pmol to µg: pmol × N × 660 pg/pmol × 1 µg/106pg = µg
To convert µg to pmol: µg × 106pg/1 µg × pmol/660pg × 1/N = pmol
2，For ssDNA
To convert pmol to µg: pmol × N × 330 pg/pmol × 1µg/106pg = µg
To convert µg to pmol: µg × 106pg/1 µg × pmol/330pg × 1/N = pmol
＃where N is the number of nucleotides and 330 pg/pmol is the average MW of a nucleotide

四， Protein Molar Conversions
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

五，Protein/DNA Conversions
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

六，Agarose Gel(%):Resolution of Linear DNA
Recommended % Agarose---- Optimum Resolution for Linear DNSize 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

七，Polyacrylamide Gel(%):Resolution of Protein 
Recommended % Acrylamide--------－ Protein Size Range
8 ---------------------- 40-200 kDa
10 ---------------------- 21-100 kDa
12----------------------－ 10-40 kDa

八，Length/M.W. of Common Nucleic Acids.
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.

九，Stardards
1. Average MW of dsDNA base pair = 600.
2. Average MW of ssDNA base =330.
3. Average MW of RNA base =340.[ｉｆｒａｍｅ][/ｉｆｒａｍｅ]