Nano, proteins, and Dr. Hongbin Li: part 1

Here’s the interview I mentioned a few days ago. I now have the answers to some questions I sent Dr. Hongbin Li (University of British Columbia) about the work he recently had published in Nature Nanotechnology (June 29, 2008 online edition). (Note: I don’t usually give links to articles behind paywalls as a lot of people won’t have access.)

Short version: Dr. Li and his team have taken a protein G and attached the fragment of an antibody to one of the protein’s binding sites with the consequence that the protein can act as either a spring or a shock absorber. They’re calling it a ‘chameleon’ nanomaterial. You can read more about it here at UBC Science or here at Nanowerk.

Dr. Li kindly took the time to answer my questions before he leaves for China this Thursday (July 10, 2008). I don’t understand the details of Dr. Li’s work very well and so my questions were largely for clarification. He’s working with a  protein G and I’ve come across G proteins in some literature research I was doing on morphine, and opioid receptors. So, my first question and Dr. Li’s response was  this:

  1. There is a super family of G proteins made up of many subsets. You have used one of these G proteins adhering an antibody fragment at one of its receptor sites. Is this more or less correct?

Response: the protein GB1 we are using has nothing to do with G proteins! GB1 is from protein G, which is a bacterial surface protein and its biological function is not known. Protein G has been widely used for purifying IgG antibodies.

I shouldn’t be surprised to find out that somebody thought it would a good idea to give two different proteins identical names simply reversing the order in which the qualifier is applied with the consequence that there’s a G protein and a protein G  They do that in French where some adjectives change their meaning based on the placement either before or after the noun (but I digress).

The next question had to do with the antibody:

  1. Is an antibody fragment what it sounds like? (i.e. It’s an antibody that’s been sliced up and you are using a fragment.)

Response: IgG antibody can be digested into fragments by proteases. For example, IgG antibody can be digested into Fc fragment and Fab fragment. We used Fc fragment in our study.

I was thinking that the antibody was being broken into fragments by some sort of mechanical process but this sounds like a biological process.

My final question in today’s posting:

  1. I’ve seen the terms ‘synthetic protein’ and ‘mutant protein’ in the various articles about your work. Do you have a preference for one of these terms over the other? And why?

Response: depending on different context, our engineered protein can be called as either synthetic protein or mutant protein. Mutant protein refers to the fact that GT18P and GV54P are mutants of GB1.

Part 2 tomorrow and thank you Dr. Hongbin Li.

One thought on “Nano, proteins, and Dr. Hongbin Li: part 1

  1. Pingback: Biomimicry, proteins, muscles, and the University of British Columbia’s Dr. Hongbin Li « FrogHeart

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