saad

Hi Guys,

I have a peptide with one tyrosine and no Try or Cys.
I used the nanodrop previously but it seems that the accuracy wasn't good to measure the affinity using ITC.
   -I want to measure the concentration using the Absorbance at 215 nm and 225nm then use this equation: ug/ml=144*(215-225)
So I need to know the concentration by uM. How can I convert to molar concentation. The MWt of the peptide is about 3237.3 Da.
   - The other question related to 215/225 I think the abo should be less than 1.5 to be accurate, is it right.

Thank you so much

Hi all,

Actually, I'm using bac to bac system from Invitrogen to express recombinant protein in insect cells so what does Bac-to-Bac system mean?.
What does P1, P2 .. stand for (Stock virus), is it passage 1, 2..

Thank you in advance

Hi all,

I've gotten a new batch of adapted to suspension sf9 insect cells from Invitogen. I use SFM-900 II at 27 degree, 120 rpm, no serum or antibiotic at all.
It is now 4 days and the cells seem not grwoing. I counted the cells after 2 days and they were 0.7 million/mL but after 4 days the same or less with no noticeable dead cells.
Is it possible for the new cells to take longer time to grow I mean for the first time.
I follow the manufature's instructions. Thawed the vial quickly and add to pre-warmed 27 mL media.
Any suggestion or recommendation will be highly appreciated.
The 1 mL cells cost more $450.!!!

Thank you so much for you help.

Hi all,

I'm working on the sf9 insect cells to generate recombinant baculovirus for protein expression.
I use bac to bac system. The cells are growing (bit slower) for now about 4-5 weeks, I've noticed some balck dots in the media and granulles inside the cells. Is it sign for conatmination? I'm still diluting the cells and the doubling time is around 48 hours and sometimes less and some times a bit longer. The cells seem to pass passage 30.
If the viability of cells are high and still growing, what are  the sign for contamination in my case.
I did the transfection and the WB showed some expression so I want to ampilfy the virus. I'm wondering about the cells if they are healthy and good for propagating the virus and protein expression later. The vaiability is > 95% with trypan blue exclusion.
Any suggestion or comments are highly appreciated.
Thank you in advance for your help as usual.