Riba:
- Fahimtar matakan tsarin furotin da wane tsari AlphaFold yayi annabta daga jeri
- Ikon karanta pLDDT da ƙimar amincewar PAE daidai da fassara ƙananan ƙarfin gwiwa a matsayin 'marasa tabbas / sassauƙa' maimakon 'ba daidai ba'
- Fahimtar wajibcin tabbatar da hasashen tsarin tare da shaidar gwaji (PDB, gwajin aiki) a cikin yanke shawara mai girma.
Sunadaran sune kwayoyin aiki na tantanin halitta: enzymes suna hanzarta halayen, masu jigilar kayayyaki suna motsa kwayoyin halitta, sunadaran tsarin suna kiyaye tantanin halitta. Abin da furotin ke yi ana kayyade shi ta hanyar naɗewar siffarsa mai girma uku (tsarinsa). Shekaru da yawa, tsinkayar tsarin furotin daga jerin sa yana daya daga cikin matsalolin da suka fi wahala a ilmin halitta. A cikin 2021, tsarin basirar ɗan adam na DeepMind da ake kira AlphaFold ya yi wani ci gaba na tarihi a cikin wannan matsalar, yana hasashen tsarin ɗaruruwan miliyoyin sunadaran zuwa kusa da daidaiton gwaji. A cikin wannan rukunin, za mu tattauna yadda ake amfani da AlphaFold da makamantansu daga mahallin ilimin halitta da nawa za ku iya amincewa da fitowar sa.
Wannan ita ce mafi girman nasarar da aka samu a ilimin halitta; Amma ko da kayan aikin tsinkaya yana da iyaka da buƙatar tabbatarwa.
Matakan tsarin gina jiki
- Tsarin farko: Amino acid jerin (tsari na haruffa).
- Tsarin na biyu: folds na gida; kamar alpha helix da beta sheet.
- Tsarin uku: siffar 3D na dukan sarkar.
- Tsarin Quaternary: Haɗin sarƙoƙi da yawa.
AlphaFold yana tsinkayar tsarin manyan makarantu (siffar 3D) daga tsarin farko (jeri). Yana yin haka ta hanyar sifofi da yake koya daga daidaitawa (MSA) na jerin abubuwan da suka danganci juyin halitta.
Karatun fitowar AlphaFold
AlphaFold baya ba da tsari kawai; Hakanan yana ba da ƙima na amincewa ga kowane tsinkaya. Fahimtar waɗannan shine mabuɗin don rashin amincewa a makance:
- pLDDT: Makin amincewa na gida tsakanin 0-100 ga kowane amino acid. Sama da 90 abin dogaro ne sosai, 70-90 abin dogaro ne, 50-70 ba shi da tabbas, ƙasa da 50 wataƙila yanki ne mai rikicewa.
- PAE (Kuskuren Haɗe-haɗen Annabta): Amintaccen matsayi na yanki tsakanin yanki; Ya nuna yadda dogara ga jeri na yanki dangi da juna a cikin manyan multidomain sunadaran.
Tukwici: Lokacin da kuka ga wuraren ƙananan pLDDT (marasa shuɗi, orange/ja) akan ƙirar AlphaFold, karanta su a matsayin "marasa kyau ko sassauƙa" maimakon "ba daidai ba." Waɗannan yankuna galibi ɓarkewar furotin ne da gaske kuma suna da mahimmancin ilimin halitta.
Mataki-mataki: bincika furotin tare da AlphaFold
- Nemo jerin: Sami jerin furotin ɗin ku daga UniProt.
- Sami tsarin: Bincika a cikin AlphaFold DB (a shirye don yawancin sunadaran) ko gudanar da ColabFold.
- Tantance amincewa: dubi pLDDT da PAE; Wadanne yankuna ne abin dogaro?
- Dubawa: Duba cikin 3D tare da PyMOL ko py3Dmol.
- Fassara: Ƙimar yankuna masu aiki kamar wurin aiki, aljihun ɗaure.
- Tabbatar: Kwatanta tsarin gwaji (X-ray/cryo-EM a PDB) idan akwai.
Hankalin wucin gadi (LLM) yana rubuta lambar a cikin waɗannan matakan (gani tare da py3Dmol, taƙaita ƙididdigewa) kuma yana bayyana ra'ayoyin. AlphaFold kanta samfurin tsinkayar tsari ce mai hankali; LLM yana taimaka muku fassara sakamakonsa.
Samfuran gaggawar da za a iya kwafi
Matsayi: Kai mataimakin tsarin halitta ne. Aiki: Bayyana makin AlphaFold pLDDT da PAE ga ɗalibin da ya kammala digiri. Bayyana abin da kowane ma'auni yake auna, waɗanne ƙofofin ake ɗaukar abin dogaro, da yadda ya kamata a fassara yankuna masu ƙarancin ƙima.
Ta yaya zan gudanar da jerin furotin da na karɓa daga UniProt a cikin ColabFold? Bayyana matakan da albarkatun / iyakokin lokaci da nake buƙatar sani. Tsawon jeri: [N] amino acid.
Rubuta lambar Python wanda ke hango fayil ɗin PDB (predicted.pdb) a cikin 3D kuma ya canza shi daidai da makin pLDDT tare da py3Dmol. Bari ya gudana a cikin Jupyter, tare da sharhi.
Ina da hasashen AlphaFold da tsarin gwaji daga PDB. Ba da lambar da sharhi wanda ya daidaita su biyun kuma ya ƙididdige RMSD (ma'anar karkata murabba'i). Bayyana adadin angstroms da ke ƙasa da RMSD ana ɗauka mai kyau.
Rauni mai ƙarfi / Ƙarfi mai ƙarfi
Rauni: "Ku gaya mani siffar wannan furotin."
Ƙarfafa: "Na yi nazarin samfurin AlphaFold na UniProt P04637 (p53 na mutum). Ƙungiyar haɗin gwiwar DNA tana da girma pLDDT (> 90), N-terminus da C-terminus suna da ƙananan pLDDT (<50). Ta yaya zan fassara wannan tsari? Bayyana cewa ƙananan ƙananan ƙididdiga sun ƙare ba tare da yin la'akari da yanayin aiki ba. "
Bambanci: Ƙarfin faɗakarwa yana da furotin na gaske, ainihin ƙima da buƙatar sharhi. Samfurin yana fassara bayanan da kuke bayarwa maimakon "tunawa" da shi.
uku mini lokuta
Shari'a 1 - Kuskure yankin da ya rikice don kuskure: ɗalibi ya kawar da ƙananan yankin pLDDT a ƙarshen furotin saboda "AlphaFold ya gane kuskure." Koyaya, wannan yanki shima yanki ne na kunnawa da ba a saba ba da gwaji. ɗalibin ya fassara yankin daidai lokacin da ƙirar ta bayyana cewa ƙananan pLDDT sau da yawa yana nuna elasticity na gaske.
Shari'a 2 - Tasirin maye gurbi: Wani mai bincike ya yi iƙirarin cewa canjin amino acid guda ɗaya ya yi "babban bambanci" a cikin ƙirar AlphaFold. Koyaya, AlphaFold baya dogaro da hasashen tasirin kwanciyar hankali na maye gurbi guda ɗaya; bambance-bambance na iya zama hayaniyar samfurin. Samfurin ya tuna da wannan iyaka kuma ya haifar da takamaiman kayan aiki (misali kayan aikin tsinkayar kwanciyar hankali).
Case 3 - Samun ta hanyar inganci: Ƙungiya ta daidaita hasashen AlphaFold tare da tsarin gwaji a cikin PDB; RMSD ya juya ya zama 1.2 angstroms (mai kyau sosai). Wannan ya ba su damar dogara ga tsinkaya da kuma tunanin aljihu mai ɗaure, kuma ya tsara gwajin yadda ya kamata. Tabbatar da ingantaccen aminci.
kwatanta jadawalin
Maki/ra'ayi
Menene ma'auni
Amintaccen bakin kofa
Farashin pLDDT
Amintaccen ginin gida (0-100)
> 90 yayi kyau sosai, <50 ba bisa ka'ida ba
PAE
Amintaccen wurin ƙetarewa
Low (duhu) mai kyau
RMSD
Yarjejeniya tare da gwaji (angström)
<2 Å gabaɗaya yana da kyau
Kuskuren gama gari
- Yin la'akari da ƙananan pLDDT a matsayin "laifi": Gabaɗaya yanki ne mara kyau/m, kar a share shi.
- Tabbatar da tasirin maye gurbi guda ɗaya tare da AlphaFold: Ba kayan aikin da ya dace don aikin ba.
- Yin watsi da ƙididdigar amincewa: ɗauka cewa gabaɗayan samfurin daidai yake da abin dogaro.
- Tsallake tsarin gwaji: Idan akwai ainihin tsari a cikin PDB, tabbatar da kwatanta shi.
- Fassara hadaddun sarƙoƙi/yawan sarƙoƙi azaman sarkar guda ɗaya: Abubuwan hulɗa suna buƙatar yanayi na musamman (AlphaFold-Multimer).
Tsanaki: AlphaFold kayan aiki ne na ban mamaki, amma hasashe ne, ba gaskiya ba. Musamman maɗaukakiyar yanke shawara kamar sabon manufa na miyagun ƙwayoyi, wurin ɗaure ko tasirin maye gurbin bai kamata a ɗauka ba tare da goyan bayan tsinkaya tare da shaidar gwaji (tsari, gwajin aiki).
Daga tsari zuwa aiki: ganin aljihu ya isa?
Samun tsarin 3D na furotin yana da ban sha'awa, amma tsari kaɗai ba ya gaya muku aiki. Kuna iya ganin wurin aiki (aljihu inda substrate ke ɗaure) na enzyme; Duk da haka, tsarin ba ya nuna ko wane nau'in kwayar halitta ne yake ɗaure, saurin aiki, ko kuma inda yake a cikin tantanin halitta. AlphaFold wuri ne na farawa: yana haifar da hasashe ("wannan aljihun yana iya ɗaure ATP"), gwajin yana gwada shi. AI yana taimaka muku ƙirƙira waɗannan hasashe da rubuta lambar da ke nazarin tsarin, amma da'awar aiki tana buƙatar tabbataccen shaida.
Wani amfani mai ƙarfi shine kwatanta tsarin: ko da jerin sunadaran sunadaran biyu sun bambanta sosai, tsarin su na iya zama iri ɗaya; wannan alama ce ga alaƙar juyin halitta mai nisa ko aiki ɗaya. Kayan aiki kamar Foldseek da sauri suna neman kamanni tsari. Samfurin yana taimaka muku fassara fitowar waɗannan kayan aikin da rubuta lambar kwatanta.
Daidaita tsarin AlphaFold na sunadaran sunadaran biyu tare da Bio.PDB, ƙididdige RMSD, kuma bayar da rahoton waɗanne yankuna ne suka mamaye kuma waɗanda suka bambanta. Yi sharhi cewa kamanni na tsari alama ce ga alaƙar aiki, amma ba shaida ba.
Complexes, hulɗa da iyakoki
Sunadaran ba sa aiki kadai, amma sau da yawa tare da abokan tarayya (sauran sunadaran, DNA, ƙananan ƙwayoyin cuta). AlphaFold-Multimer na iya yin hasashen abubuwan gina jiki-gina jiki; amma shi kadai bai isa ba ga iko da gaskiyar mu'amala. Lokacin da samfurin ya annabta cewa "sunadarai biyu suna hulɗa," wannan shine hasashe na farko; ya kamata a tabbatar da gwaje-gwaje irin su co-immunoprecipitation (co-IP). Yi amfani da AI don fahimtar inda waɗannan kayan aikin suka dace da kuma tantance ƙarfin fitarwa; Ƙididdiga masu aminci (musamman PAE) sun fi mahimmanci fiye da kowane lokaci a cikin tsinkaya mai rikitarwa.
AlphaFold ba shine kawai zaɓi ba
Yayin da AlphaFold majagaba ne, ba shine kawai kayan aiki ba. ESMFold (Meta) yana aiwatar da tsinkaya mai sauri daga jeri ɗaya, ba tare da buƙatar daidaitawar juyin halitta ba; Ya dace don duba manyan jeri-jeri, amma gabaɗaya ya yi ƙasa da daidai fiye da AlphaFold. RoseTTAFold wani zaɓi ne mai ƙarfi. AlphaFold3 da sabbin nau'ikan sabbin nau'ikan iri kuma sun haɗa da furotin-ligand da rukunin furotin-nucleic acid. Kuna iya tuntuɓar AI wanda kayan aiki ya dace da matsalar gini (gudu ko daidaito, sarkar guda ɗaya ko hadaddun); Amma ku tuna karanta ma'aunin amincin kowane kayan aiki akan sikelin sa: abin da ake la'akari da maki "mai kyau" a cikin kayan aiki ɗaya ana fassara shi daban a cikin wani.
A takaice
AlphaFold ya canza ilimin halitta ta hanyar tsinkayar tsarin furotin daga jerin sa. Duk da haka, ya kamata a karanta abin fitar da shi tare da makin amincewa (pLDDT, PAE); Ya kamata a fassara ƙananan matakan amincewa da "marasa tabbas / sassauƙa" maimakon "ba daidai ba". Hankali na wucin gadi (LLM) yana taimaka muku bayyana waɗannan maki, rubuta lambar gani, da kwatanta su da tsarin gwaji. Don yanke shawara mai girma, dole ne a goyi bayan tsinkaya ta hanyar ingantaccen shaida.
Aikin aikace-aikace
Zaɓi furotin (misali wani enzyme da kuke sha'awar). Nemo tsarin sa daga UniProt da tsarin sa daga AlphaFold DB. Shin AI ya rubuta kuma ya gudanar da lambar tare da py3Dmol wanda ke canza tsarin daidai da pLDDT. Gano manyan yankuna masu aminci da ƙarancin ƙarfi. Shin ƙirar ta fassara yuwuwar mahimmancin ilimin halitta na yankuna masu ƙarancin ƙarfin gwiwa kuma bincika tsarin gwaji a cikin PDB.
jerin abubuwan dubawa
- [ ] Na kimanta tsarin tare da maki pLDDT/PAE.
- [ ] Na fassara ƙananan matakan amincewa da "marasa tabbas/m", ba "kuskure ba".
- [ ] Ba ni da kwarin gwiwa sosai ga AlphaFold don tasirin maye gurbi guda ɗaya.
- [] Na kwatanta shi da tsarin gwaji (PDB), idan akwai.
- [ ] Na yi tunani game da kayan aikin da ya dace don polychain/complex.
- [ ] Na goyi bayan babban sakamako tare da tabbataccen shaida.