Te Pānga o te pH ki te Mahi a te Whākōkī
Ko ngā whākōkī he ngota koiora—ko te nuinga he pūmua—e mahi ana hei whakakorikori i ngā tauhohenga matū i roto i ngā rauropi ora. Ki te kore he whākōkī, ka tino puhoi te nuinga o ngā tauhohenga pākia, ā, kāore e taea te pupuri i te ora. Heoi, ko te kaha o ngā whākōkī ki te tere ake i ngā tauhohenga kāore i te whakawhirinaki ki te āhua. He kaha te awe o ngā āhuatanga taiao ki te mahi whākōkī, ko tētahi o ngā mea tino nui ko te pH (waikawa). Ka taea e ngā panoni o te pH te meinga ngā whākōkī kia mahi pai, kia whakaitihia ā rātou mahi, kia ngaro rānei ā rātou mahi.
Te ariā o te pH me tōna whanaungatanga ki ngā pūnaha koiora
Ko te pH he ine i te kukū o ngā katote hauwai (H⁺) i roto i tētahi otinga. Ko te tauine pH kei waenga i te 0 ki te 14: ko te pH 7 he kūpapa, ko te pH i raro i te 7 he waikawa, ā, ko te pH i runga ake i te 7 he kawakore. I roto i ngā pūnaha koiora, ka puritia te pH i roto i tētahi awhe motuhake mā roto i ngā tikanga ārai kia taea ai e ngā tauhohenga matū koiora te haere tonu me te pumau.
He pH motuhake tō ia okana, tō ia pūtau rānei. Hei tauira, he tino waikawa te pH o te puku tangata (tata ki te 1–3) hei āwhina i te nakunaku, ko te whekau iti ia he kawakore ake (tata ki te 7–8). Ko te cytoplasm o te pūtau he tata tonu ki te kūpapa (tata ki te 7,2). Ehara i te mea tūpono noa iho ēnei rerekētanga o te pH i waenga i ēnei wāhanga: kua "whakaurua" ngā whākōkī e mahi ana i roto i ia wāhanga ki ēnei āhuatanga.
He aha te pānga o te pH ki te mahi a te whākōkī?
Ko te mahi a te whākōkī e whakawhirinaki ana ki te āhua toru-ahu o te whākōkī me ngā āhuatanga matū o ōna rōpū mahi. He "wāhi hohe" tō ngā whākōkī, he rohe motuhake e herea ai te matū (te matū tauhohe) ka hurihia hei hua. Ko te angitu o te tauhohenga whākōkī e tino whakatauhia ana e te pai o te āhua o te pae hohe, tōna utu hiko, me tōna kaha ki te hanga hononga rangitahi ki te matū.
Ka pā te pH ki te mahi a te whākōkī mā roto i ngā tikanga e rua e whai ake nei:
1. Ngā panonitanga o te utunga (whakakoiora) o ngā rōpū waikawa-pūtake i runga i ngā whākōkī me ngā matūriki
He mea tito ngā pūmua i ngā waikawa amino he rōpū ka taea te whakakōhiko (hei tauira, –COOH/–COO⁻, –NH₃⁺/–NH₂). Ina huri te pH, ka ngaro, ka whiwhi rānei ētahi rōpū i runga i te whākōkī i ngā porotona (H⁺). Nō reira, ka huri te utu hiko i te pae hohe. He mea nui te utu tika hei kukume i ngā matūriki, hei whakau i ngā āhua whakawhiti, hei whakahaere rānei i ngā mahi whakatere motuhake.
2. Ngā panonitanga o te hanganga (te āhua) o te whākōkī
Ka whakauhia te hanganga pūmua e ngā hononga hauwai, ngā hononga ion (ngā piriti tote), ngā taunekeneke hydrophobic, me ētahi hononga disulfide. Ka taea e ngā huringa o te pH te whakararu i ēnei hononga mā te whakarerekē i te utu o ngā toenga waikawa amino. Mena he nui te whakararuraru, ka taea e te whākōkī te whakarerekē i te āhua (denaturation) kia kore ai e pai te pae hohe mō te substrate.
Ara, ka pā te pH ki te "matū" me te "āhua" o te whākōkī—e rua ngā mea tino nui mō tana mahi.
pH tino pai: te pūwāhi mahi pai rawa atu o te whākōkī
He pH tino pai tō ia whākōkī, arā, ko te pH e teitei rawa ana te mahi whakaterenga. Mēnā ka neke te pH mai i tēnei wāhi, ka heke te tere o te tauhohenga . Ko te whanaungatanga i waenga i te pH me te mahi whākōkī ka whakaahuatia pinepinetia hei kōpiko āhua pere: ka piki haere ki te pH tino pai, kātahi ka heke ina tino waikawa, ka tino taketake rānei te pH.
Heoi, kāore te āhua o te kōpiko i te ōrite i ngā wā katoa. I roto i ētahi whākōkī, ka kaha ake te hekenga o te mahi i te taha waikawa, i te taha taketake rānei , i runga i te rōpū e tino hira ana mō te whakaterenga.
Ngā tauira o ngā pH tino pai o te whākōkī e kōrerohia whānuitia ana:
– Pepsin (te whākōkī nakunaku pūmua i roto i te puku): ko te pH tino pai kei te 2. Ka tino kaha te mahi a tēnei whākōkī i roto i ngā āhuatanga waikawa nui.
– Te amylase huware (te wahie māngaro i roto i te waha): Ko te pH tino pai kei te 6,5–7. He tata tonu te waha ki te kūpapa, e āhei ai te amylase ki te mahi pai i te tīmatanga o te nakunaku o te kai.
– Trypsin (he whākōkī nakunaku pūmua i roto i te whekau iti): Ko te pH tino pai kei te 8. Mā te āhua kawakore ake i roto i te whekau iti ka tautoko i tana mahi.
Ko tēnei rerekētanga o te pH tino pai e whakaatu ana he hononga tata te wāhi o te mahi a te whākōkī i roto i te tinana ki te taiao pH e wātea ana.
Te pānga o te pH tino nui: te hekenga o te mahi ki te denaturation
Ina kei te pH o ngā whākōkī he tawhiti rawa atu i te pH tino pai, he maha ngā mea ka puta:
1. Te hekenga o te hononga whākōkī ki te matūriki
Mā ngā panonitanga o te utu i runga i te pae hohe ka uaua ake te here o te matūriki. Nō reira, ka heke te maha o ngā matatini whākōkī-mātūriki, ā, tere tauhohenga whakaiti
2. Te whakararuraru o te taahiraa whakakorikori
Ko ētahi whākōkī me whakapūtātia, me tango rānei i te pūpūtātia ētahi rōpū kia puta ai te tauhohenga. Ka taea e te pH hē te "raka" i ēnei rōpū ki roto i te āhua kore mahi.
3. Te whakakorenga o te pūmua
I te pH tino tiketike, ka taea te whakararuraru i ngā hononga me ngā taunekeneke e pupuri ana i te takai pūmua. Ka ngaro te hanganga tuatoru o ngā whākōkī, ka huri ō rātou pae hohe, ā, ka ngaro tā rātou mahi. I roto i te nuinga o ngā wā, kāore e taea te whakakore i te denaturation, inā koa ka huihui ngā whākōkī (aggregate).
Me mōhio ehara i te mea ko ngā hekenga katoa o te mahi ka mutu te hanga matū. I ētahi wā ka pāngia ngā whākōkī e ngā huringa o te ionization ka hoki anō ki te āhua noa ina whakahokia te pH ki te awhe tino pai.
pH me te whakahaere pākia
I roto i ngā pūtau, ehara te pH i te "āhua papamuri" anake, engari ka taea hoki te noho hei wāhanga o te whakahaere pākia. Ka taea e ngā pūtau te whakarerekē i te pH ā-rohe hei whakahohe, hei whakakore rānei i ngā whākōkī motuhake. Hei tauira, ko ngā whekau pēnei i ngā lysosomes he pH waikawa (tata ki te 4,5–5), e whakahohe ana i ngā whākōkī hydrolytic hei nakunaku i ngā macromolecules. Ka iti ake te kaha o ēnei whākōkī mēnā ka turuturu ki roto i te cytoplasm kūpapa ake, ā, ka whakaiti i te mōrearea o te kino o te pūtau.
Hei tāpiri atu, ka puta pea ngā panoni pH i raro i ētahi āhuatanga ā-tinana. Hei tauira, i te wā e whakakorikori tinana ana, ka taea e te kohi o te waikawa lactic te whakaheke i te pH uaua. Ka taea e tēnei hekenga o te pH te pā ki ngā whākōkī pākia pūngao, ā, ka whai wāhi atu ki te ngenge.
Te whakamahinga o te awe pH i roto i te oranga o ia rā me te ahumahi
He whānuitia te whakamahinga o te mārama ki te pH tino pai o ngā whākōkī i roto i ngā mara maha:
– Ahumahi kai: Ka whakamahia ngā whākōkī pēnei i te pectinase i roto i te tukatuka wai hei whakamārama i te wai. Ka whakahaeretia te tukanga i tētahi pH motuhake hei whakarite i te mahi tino pai o te whākōkī.
– Ngā hopi horoi whākōkī: Kua hangaia ngā protease me ngā lipase i roto i ngā hopi horoi kia kaha ki te pH kawakore e kitea ana i roto i ngā wai horoi.
– Te Whakapūkara: Ko te hanga miraka kawa, tīhi, inu rānei kua whakapūkarahia he whākōkī moroiti e pāngia ana e te pH. Mā te whakahaere i te pH ka āwhina i te pupuri i te hua me te reka o te hua.
– Te hangarau koiora me ngā taiwhanga: Ko ngā tauhohenga whākōkī pēnei i te PCR (mā te whakamahi i te whākōkī DNA polymerase) me whai i tētahi arai me tētahi pH motuhake hei pupuri i te pumau o te whākōkī me te whai huatanga o te tauhohenga, ahakoa he nui ake te mana o te pāmahana.
Whakamutunga
He mea nui te pH hei awe i te mahi a te whākōkī nā te mea ka taea e ia te whakarerekē i te utu o ngā rōpū mahi me te hanganga toru-ahu o ngā whākōkī, inā koa i te pae hohe. He pH tino pai tō ia whākōkī e whakaata ana i te taiao e mahi ana ia. Ina neke rawa te pH mai i te tino pai, ka heke te mahi a te whākōkī nā te iti o te hononga ki te papa, te whakararuraru i ngā tikanga whakatere, tae noa ki te denaturation. Ehara i te mea he mea nui te mārama ki te whanaungatanga i waenga i te pH me te mahi whākōkī i roto i te koiora me te hauora anake, engari he tino whai hua hoki i roto i te kai, te hopi horoi, te whakapūkara, me ngā tono hangarau koiora.
Ki te hiahia koe, ka taea e au te tāpiri i tētahi wāhanga "tikanga whakamātautau māmā" hei whakamātautau i te pānga o te pH ki ngā whākōkī (hei tauira, te amylase) me ngā taurangi, ngā taputapu me ngā rauemi, me pēhea hoki te tātari i ngā hua.
