chemical competent cells - From a Biojoe's pm (May/31/2007 )

Chemcally competent cells

1. subculture 300 ul overnight E. coli culture into 10 ml LB ( in 50 ml centrifuge tube), shaking, 37℃, 1-2 hrs
2. OD550 = 0.2-0.4
3. Centrifugation: 3000 rpm, 15 min; save pellet, decant the supernatant completely
4. Dissolve the pellet with 5ml ice/steriliezed 100mM CaCl2
5. Incubation on ice for 30 minutes
6. centrifugation: 4℃, 3000 rpm, 15 min; save pellet, discard supernatant
7. Resuspend the pellet with 1-2 ml ice/sterilized 100mM CaCl2
8. Incubation for 1 hr (or 12-16 hr, best) on ice
9. aliquot to eppendorf: 150 ul each, in 15% glycerol, store in -80℃ freezer

thanks to share the protocol with us. but i dont understand the term "chemically". what does it mean here?? can i use this competent cell for transformation of plasmid DNA???

i need to make competent cell soon, i could try your protocol

i think chemical is opposed to electrocompetent cells.
I call them usually thermocompetent cells but whatever.
They give normally less transformants as electroporation, but for large vectors or for liimting reombination events they're better

I was confused by the term 'chemically competent' until I realised that it just means 'made competent through the use of chemicals' particularly CaCl2. The reason we don't call them 'heat shock competent' is because you can transform them without heat shocking if you like (this is the way I do it).