Re: [ccp4bb] To solve the problem of an extremely asymmetric

2020-12-09 Thread Rezaul Karim
Exactly. Without a picture of SEC profile it's even difficult to decipher the meaning of "extremely asymmetric peak shape". Beside that, one domain or multi-domain protein, extended N-term or C-term loops containing constructs, column, load (weight & vol) and flow rate - any one of these could

Re: [ccp4bb] Coming July 29: Improved Carbohydrate Data at the PDB -- N-glycans are now separate chains if more than one residue

2020-12-09 Thread Marcin Wojdyr
Dear Jasmine, thank you for this explanation. It's the best explanation of this remediation I've read. The use of IDs may confuse people, so I'd like to reiterate it and ask for clarification. Every residue in the mmCIF format has three (3) independent chain IDs assigned to it (and three

Re: [ccp4bb] when does non-isomorphism become a habit?

2020-12-09 Thread Ailong Ke
Good thoughts, although there are always exceptions. For example, if a crystal contact is mediated by an extended domain that is capable of adopting multiple conformations (due to elbow motion, for example), then it may allow multiple crystal forms. It happens a lot in RNA crystals, but can

Re: [ccp4bb] To solve the problem of an extremely asymmetric peak shape obtained from gel filtration chromatography

2020-12-09 Thread Artem Evdokimov
Probably a good idea to share an image :) worth many words... Artem On Wed, Dec 9, 2020, 9:17 AM wrote: > Dear All > There is a 43kd protein purified via Ni-chelating affinity > chromatography, anion exchange chromatography and gel filtration > chromatography in sequence. However the

[ccp4bb] Job Vacancy: Postdoctoral research fellow position available in Therapeutics Discovery Division at MD Anderson Cancer Center

2020-12-09 Thread Leonard,Paul G
Hi, A postdoctoral position is currently available in the Structural Chemistry group, part of the Institute for Applied Cancer Science (IACS) within the Therapeutics Discovery Division of MD Anderson Cancer Center. Our mission is to integrate novel biological insights with drug discovery

Re: [ccp4bb] To solve the problem of an extremely asymmetric peak shape obtained from gel filtration chromatography

2020-12-09 Thread Ross Robinson
It would be sensible to analyse the state of your purified protein further. * (SEC in reasonable salt conc containing buffer – this is standard practice) * Analytical ion exchange of purified protein - are there different states? * SEC (in reasonable buffer) in line with MALS – is

Re: [ccp4bb] Coming July 29: Improved Carbohydrate Data at the PDB -- N-glycans are now separate chains if more than one residue

2020-12-09 Thread Jasmine Young
Dear Robbie, In the case that only single monosaccharide was modelled at glycosylation site with a known oligosaccharide sequence, technically the software cannot generate glycosidic linkages, linear descriptors for sequences, 2D SNFG images, etc. Therefore, this single monosaccharide cannot

Re: [ccp4bb] To solve the problem of an extremely asymmetric peak shape obtained from gel filtration chromatography

2020-12-09 Thread Javier Gonzalez
Hello, I agree with Roger, you should definitely try to increase the salt concentration to get rid of non specific binding impurities. And if that doesn't work, you can try purifying your protein under denaturing conditions by adding one refolding step in the column. Good luck, Javier On Wed, Dec

Re: [ccp4bb] To solve the problem of an extremely asymmetric peak shape obtained from gel filtration chromatography

2020-12-09 Thread Roger Rowlett
Salt concentrations less than 100 mM can lead to nonspecific adsorption to the gel exclusion media, potentially leading to band broadening, and delayed elution. Overloading gel exclusion columns (more than 2-4% Vt) can also lead to elution band artifacts. Check these issues first. Roger Rowlett

[ccp4bb] To solve the problem of an extremely asymmetric peak shape obtained from gel filtration chromatography

2020-12-09 Thread
Dear All There is a 43kd protein purified via Ni-chelating affinity chromatography, anion exchange chromatography and gel filtration chromatography in sequence. However the chromatogram obtained showed an extremely asymmetric peak shape. The aggregation forms of proteins are mainly in

Re: [ccp4bb] AlphaFold: more thinking and less pipetting (?)

2020-12-09 Thread Bryan Lepore
> On Dec 9, 2020, at 07:45, Harry Powell - CCP4BB > <193323b1e616-dmarc-requ...@jiscmail.ac.uk> wrote: > > ... GDT_TS (Global Distance Test - Total Score - you can look it up on > Wikipedia Thanks, this is helpful. Wikipedia: “The primary GDT assessment uses only the alpha carbon

Re: [ccp4bb] AW: [ccp4bb] External: Re: [ccp4bb] AlphaFold: more thinking and less pipetting (?)

2020-12-09 Thread Patrick Shaw Stewart
>they can maintain an advantage through several routes - they can > publish in patents (so people can see what they’ve done, but not legally > implement it ) In Europe and I think some other countries, inventions can only be patented if they have *industrial applicability.* In any case,

Re: [ccp4bb] AlphaFold: more thinking and less pipetting (?)

2020-12-09 Thread Harry Powell - CCP4BB
The “something” is what gives them their edge (and which they’ve hinted at, but avoided being explicit)… The main quality score used to distinguish their results is GDT_TS (Global Distance Test - Total Score - you can look it up on Wikipedia like I did). Although it doesn’t say in Wikipedia,

Re: [ccp4bb] AlphaFold: more thinking and less pipetting (?)

2020-12-09 Thread Bryan Lepore
On Dec 9, 2020, at 07:16, Harry Powell wrote: > > ...the important thing is [...] they’ve done something that no-one else has > managed to do as well in spite of years of trying. What, precisely, is the “something”? Exactly how much better than second place? Was the scoring the same across

Re: [ccp4bb] AW: [ccp4bb] External: Re: [ccp4bb] AlphaFold: more thinking and less pipetting (?)

2020-12-09 Thread Harry Powell - CCP4BB
Hi Actually, since Deep Mind is a commercial organization (funded by shareholders and people who buy their services), I don’t think they are subject to the same rules as academia as regards making their source code public. It would be very nice if they would (could?) make their code public,

Re: [ccp4bb] External: Re: [ccp4bb] AlphaFold: more thinking and less pipetting (?)

2020-12-09 Thread Matthew Snee
It seems immensely powerful, but my impression is it shows just how much information can be extrapolated from the PDB if a technique that can make use of "deep similarity" can be employed. Obviously alphafold2 can make use of relationships that arent limited to direct homology, but if there is

[ccp4bb] AW: [ccp4bb] External: Re: [ccp4bb] AlphaFold: more thinking and less pipetting (?)

2020-12-09 Thread Hughes, Jonathan
i think the answer to all these doubts and questions is quite simple: the AlphaFold2 people must make all details of their methods public (source code) and, as would probably be necessary, open their system for inspection and use by independent experts. isn't that what peer review and

Re: [ccp4bb] External: Re: [ccp4bb] AlphaFold: more thinking and less pipetting (?)

2020-12-09 Thread Mark J van Raaij
on the day the news came out, I did wonder if the AlphaFold2 team somehow had access to all the preliminary PDB files sent around via Gmail (which belongs to the same company), but more as a joke/conspirational thought. "our" target T1052, was also predicted very well by domains and as a

Re: [ccp4bb] External: Re: [ccp4bb] AlphaFold: more thinking and less pipetting (?)

2020-12-09 Thread Cedric Govaerts
Dear All After about 10 (!) years of (very) hard work we solved the structures of our dearest membrane transporter. Dataset at 2.9 And resolution, fairly anisotropic, experimental phasing, and many long nights with Coot and Buster to achieve model refinement. The experimental structure

Re: [ccp4bb] Coming July 29: Improved Carbohydrate Data at the PDB -- N-glycans are now separate chains if more than one residue

2020-12-09 Thread Robbie Joosten
Dear Jasmine, I have a few questions about this bit: // As some users pointed out, single NAG could be just a part of the glycan that the author chose to build, as most natural N-glycans must have stem of a common core of 5 monosaccharides or its fucosylated version, such as those modeled in

Re: [ccp4bb] when does non-isomorphism become a habit?

2020-12-09 Thread vincent Chaptal
Dear James, I'll second Manferd's post. We have a membrane protein that crystallizes with a continuum of cell dimensions, so different that you can't merge the data to reach full completeness, but you could manage to gain MR solutions for some discrete states of the continuum and ending up in