{"id":62924,"date":"2026-09-12T09:12:44","date_gmt":"2026-09-12T09:12:44","guid":{"rendered":"https:\/\/stagvape.com\/recenzii\/tobacco-plants-nicotine-biosynthesis-pathway"},"modified":"2026-09-13T09:39:50","modified_gmt":"2026-09-13T09:39:50","slug":"tobacco-plants-nicotine-biosynthesis-pathway","status":"publish","type":"post","link":"https:\/\/stagvape.com\/ro\/studii\/tobacco-plants-nicotine-biosynthesis-pathway","title":{"rendered":"Oamenii de \u0219tiin\u021b\u0103 afl\u0103 cum produc plantele de tutun nicotin\u0103 pentru a permite tutunul cu con\u021binut redus de nicotin\u0103"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Biochimi\u0219tii de la Universitatea din York, \u00een colaborare cu parteneri interna\u021bionali, au finalizat identificarea c\u0103ii enzimatice pe care plantele de tutun o folosesc pentru a asambla nicotina din blocuri chimice simple. Descoperirea rezolv\u0103 o enigm\u0103 biologic\u0103 existent\u0103 de c\u00e2nd chimi\u0219tii au extras pentru prima dat\u0103 nicotina din frunzele de tutun, \u00een 1828.<\/p>\n\n<p class=\"wp-block-paragraph\">Descoperirile clarific\u0103 mecanismele genetice \u0219i biochimice responsabile de producerea alcaloidului care provoac\u0103 dependen\u021b\u0103. Dincolo de implica\u021biile pentru cultivarea agricol\u0103 a tutunului, cercetarea ofer\u0103 instrumente moleculare pentru eliminarea nicotinei din speciile de tutun utilizate ca platforme de produc\u021bie pentru produse farmaceutice, vaccinuri \u0219i proteine de diagnostic.<\/p>\n\n<p class=\"wp-block-paragraph\">\u201eEste un moment important \u00een \u0219tiin\u021ba plantelor \u0219i biochimie, deoarece avem acum r\u0103spunsul pe care \u00eel c\u0103ut\u0103m de peste 200 de ani!\u201d, a declarat dr. Benjamin Lichman de la Centrul pentru Produse Agricole Inovatoare al Universit\u0103\u021bii din York.<\/p>\n\n<h2 class=\"wp-block-heading\">C\u0103utarea de dou\u0103 secole a biosintezei nicotinei<\/h2>\n\n<p class=\"wp-block-paragraph\">Nicotina func\u021bioneaz\u0103 \u00een principal ca mecanism de ap\u0103rare alcaloid \u00een natur\u0103. Plantele de tutun produc compusul \u00een r\u0103d\u0103cini \u0219i \u00eel transport\u0103 c\u0103tre frunze pentru a descuraja insectele erbivore \u0219i animalele care pasc. Atunci c\u00e2nd este consumat\u0103 de oameni, molecula se leag\u0103 direct de receptorii nicotinici ai acetilcolinei din sistemul nervos, ac\u021bion\u00e2nd ca stimulant \u0219i gener\u00e2nd dependen\u021b\u0103 fizic\u0103.<\/p>\n\n<p class=\"wp-block-paragraph\">Timp de decenii, cercet\u0103torii au \u00een\u021beles precursorii chimici de baz\u0103 necesari form\u0103rii nicotinei. Analizele structurale au confirmat c\u0103 molecula este alc\u0103tuit\u0103 din dou\u0103 inele heterociclice distincte, unite printr-o singur\u0103 leg\u0103tur\u0103 carbon-carbon:<\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>Un inel de piridin\u0103:<\/strong>\u00a0Derivat din acid nicotinic (o form\u0103 de vitamina B3).<\/li>\n\n\n\n<li><strong>Un inel de pirolidin\u0103:<\/strong>\u00a0Format din cationul N-metilpiroliniu derivat din aminoacizi.<\/li>\n<\/ul>\n\n<p class=\"wp-block-paragraph\">\u00cen ciuda cunoa\u0219terii materiilor prime, oamenii de \u0219tiin\u021b\u0103 nu au putut identifica mecanismul catalitic responsabil de legarea celor dou\u0103 inele. \u00cencerc\u0103rile de a observa condensarea direct\u0103 a acestor molecule \u00een medii de laborator au fost blocate \u00een mod repetat, deoarece acidul nicotinic r\u0103m\u00e2ne stabil din punct de vedere chimic \u00een condi\u021bii biologice standard. F\u0103r\u0103 o etap\u0103 de activare, bariera energetic\u0103 pentru legarea inelelor a r\u0103mas prea ridicat\u0103 pentru ca enzimele vegetale cunoscute s\u0103 o poat\u0103 dep\u0103\u0219i.<\/p>\n\n<figure class=\"wp-block-image size-large\"><img fetchpriority=\"high\" decoding=\"async\" width=\"1024\" height=\"376\" src=\"https:\/\/stagvape.com\/wp-content\/uploads\/2026\/09\/image-2-1024x376.png\" alt=\"Cum produc plantele de tutun nicotin\u0103\" class=\"wp-image-62515\" title=\"\" srcset=\"\/\/stagvape.com\/wp-content\/uploads\/2026\/09\/image-2-1024x376.png 1024w, \/\/stagvape.com\/wp-content\/uploads\/2026\/09\/image-2-300x110.png 300w, \/\/stagvape.com\/wp-content\/uploads\/2026\/09\/image-2-768x282.png 768w, \/\/stagvape.com\/wp-content\/uploads\/2026\/09\/image-2-1536x564.png 1536w, \/\/stagvape.com\/wp-content\/uploads\/2026\/09\/image-2.png 1920w\" sizes=\"(max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n<h2 class=\"wp-block-heading\">Mecanismul: glucozilare criptic\u0103 de activare<\/h2>\n\n<p class=\"wp-block-paragraph\">Echipa Universit\u0103\u021bii din York a descoperit c\u0103 planta de tutun ocole\u0219te aceast\u0103 barier\u0103 chimic\u0103 folosind un intermediar nea\u0219teptat: glucoza. Planta leag\u0103 temporar o molecul\u0103 de zah\u0103r de glucoz\u0103 de acidul nicotinic, destabiliz\u00e2nd compusul \u0219i reduc\u00e2nd energia de activare necesar\u0103 pentru reac\u021biile enzimatice ulterioare.<\/p>\n\n<p class=\"wp-block-paragraph\">Aceast\u0103 strategie biologic\u0103, denumit\u0103 <strong>glucozilare criptic\u0103 de activare<\/strong>, ac\u021bioneaz\u0103 ca un m\u00e2ner molecular temporar. Odat\u0103 ce glucoza activeaz\u0103 precursorul, alte enzime cupleaz\u0103 inelul cu N-metilpiroliniul. Imediat ce se formeaz\u0103 leg\u0103tura structural\u0103, o alt\u0103 enzim\u0103 separ\u0103 zah\u0103rul din complex, l\u0103s\u00e2nd \u00een urm\u0103 o molecul\u0103 de nicotin\u0103 finalizat\u0103.<\/p>\n\n<p class=\"wp-block-paragraph\">Deoarece molecula de glucoz\u0103 se deta\u0219eaz\u0103 \u00eenainte ca produsul final s\u0103 p\u0103r\u0103seasc\u0103 ansamblul enzimatic, aceasta nu a l\u0103sat nicio urm\u0103 chimic\u0103 \u00een alcaloidul final. Aceast\u0103 natur\u0103 tranzitorie explic\u0103 de ce genera\u021bii de chimi\u0219ti analitici nu au reu\u0219it s\u0103 izoleze etapele intermediare ale c\u0103ii.<\/p>\n\n<p class=\"wp-block-paragraph\">\u201eEnigma modului \u00een care plantele de tutun produc nicotin\u0103 dateaz\u0103 \u00eenc\u0103 de la sf\u00e2r\u0219itul anilor 1820, c\u00e2nd nicotina a fost extras\u0103 pentru prima dat\u0103 din plante\u201d, a spus Lichman. \u201eCu aceste noi cuno\u0219tin\u021be putem elimina sau reutiliza nicotina produs\u0103 \u00een mod natural de plant\u0103 \u0219i putem crea instrumente biotehnologice mai bune; exist\u0103, de asemenea, un poten\u021bial interesant de a adapta \u00een viitor sistemul de formare a nicotinei din tutun pentru a produce compu\u0219i farmaceutici utili.\u201d<\/p>\n\n<h2 class=\"wp-block-heading\">Cascada de patru enzime<\/h2>\n\n<p class=\"wp-block-paragraph\">Pentru a verifica secven\u021ba reac\u021biilor, echipa de cercetare a izolat \u0219i purificat patru enzime distincte din \u021besuturi de tutun, reconstituind \u00eentreaga cale metabolic\u0103 \u00een afara celulei vii.<\/p>\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th class=\"has-text-align-left\" data-align=\"left\">Enzim\u0103<\/th><th class=\"has-text-align-left\" data-align=\"left\">Func\u021bie biochimic\u0103<\/th><th class=\"has-text-align-left\" data-align=\"left\">Rol \u00een cale<\/th><\/tr><\/thead><tbody><tr><td><strong>NaGT<\/strong><\/td><td>Glucoziltransferaz\u0103<\/td><td>Ata\u0219eaz\u0103 glucoza de acidul nicotinic pentru a crea un intermediar activat.<\/td><\/tr><tr><td><strong>NaGR<\/strong><\/td><td>Reductaz\u0103<\/td><td>Transfer\u0103 atomi de hidrogen pentru a reduce molecula precursor activat\u0103.<\/td><\/tr><tr><td><strong>NicGS<\/strong><\/td><td>Sintaz\u0103 de cuplare<\/td><td>Asigur\u0103 controlul stereochimic, produc\u00e2nd (S)-nicotin\u0103 activ\u0103 biologic.<\/td><\/tr><tr><td><strong>NicGH<\/strong><\/td><td>Glucozidaz\u0103 \/ hidrolaz\u0103<\/td><td>Hidrolizeaz\u0103 \u0219i elimin\u0103 marcajul temporar de glucoz\u0103, rezult\u00e2nd nicotin\u0103 pur\u0103.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n<p class=\"wp-block-paragraph\">Folosind cristalografie cu raze X de \u00eenalt\u0103 rezolu\u021bie, autorul principal Benjamin Schwabe a determinat structurile tridimensionale ale NaGR \u0219i NicGS la rezolu\u021bie atomic\u0103. Modelele structurale au ar\u0103tat c\u0103 NicGS orienteaz\u0103 fizic intermediarii reac\u021biei \u00een situsul s\u0103u de legare pentru a direc\u021biona configura\u021bia spa\u021bial\u0103 a leg\u0103turii finale.<\/p>\n\n<p class=\"wp-block-paragraph\">Acest control structural este decisiv din punct de vedere biologic. Moleculele biologice exist\u0103 adesea ca enantiomeri chirali \u2014 versiuni \u00een oglind\u0103 ale aceleia\u0219i formule chimice. Plantele de tutun produc aproape exclusiv (S)-nicotin\u0103, izomerul optic care se leag\u0103 eficient de receptorii neurologici ai mamiferelor. C\u00e2nd cercet\u0103torii au testat calea f\u0103r\u0103 NicGS, sistemul a produs un amestec racemic necontrolat al ambilor izomeri, st\u00e2ngaci \u0219i dreptaci, demonstr\u00e2nd c\u0103 NicGS determin\u0103 precizia stereochimic\u0103 a tutunului natural.<\/p>\n\n<h2 class=\"wp-block-heading\">Verificarea \u00een sisteme de plante vii<\/h2>\n\n<p class=\"wp-block-paragraph\">Dup\u0103 sinteza de laborator f\u0103r\u0103 celule, cercet\u0103torii au validat calea enzimatic\u0103 \u00een \u021besut vegetal viu. Ei au introdus genele care codific\u0103 cele patru enzime \u00een <em>Nicotiana benthamiana<\/em>, o rud\u0103 s\u0103lbatic\u0103 australian\u0103 a tutunului, utilizat\u0103 pe scar\u0103 larg\u0103 \u00een cercetarea agricol\u0103 \u0219i farmaceutic\u0103.<\/p>\n\n<p class=\"wp-block-paragraph\">Plantele modificate au produs molecule de nicotin\u0103 marcate care au reflectat profilele plantelor naturale. \u00cen plus, prin dezactivarea unor gene individuale din cadrul cascadei, cercet\u0103torii au verificat fiecare etap\u0103:<\/p>\n\n<ul class=\"wp-block-list\">\n<li>Suprimarea <strong>NicGH<\/strong> a determinat plantele s\u0103 acumuleze precursori stabili de nicotin\u0103 lega\u021bi de glucoz\u0103, f\u0103r\u0103 a produce nicotin\u0103 liber\u0103.<\/li>\n\n\n\n<li>Omiterea <strong>NicGS<\/strong> a perturbat stereospecificitatea c\u0103ii, confirm\u00e2nd rolul s\u0103u regulator \u00een mediile celulare vii.<\/li>\n<\/ul>\n\n<h2 class=\"wp-block-heading\">\u00cembun\u0103t\u0103\u021birea platformelor de tutun pentru agricultura molecular\u0103<\/h2>\n\n<p class=\"wp-block-paragraph\">Identificarea acestor patru enzime are utilitate direct\u0103 pentru bioproduc\u021bia modern\u0103. De\u0219i tutunul comercial r\u0103m\u00e2ne sinonim cu \u021big\u0103rile, biologii specializa\u021bi \u00een plante utilizeaz\u0103 frecvent specii de tutun pentru agricultura molecular\u0103 \u2014 folosind \u021besuturi vegetale cu cre\u0219tere rapid\u0103 ca bioreactoare pentru a sintetiza proteine medicale, anticorpi monoclonali \u0219i antigene vaccinale.<\/p>\n\n<p class=\"wp-block-paragraph\"><em>Nicotiana benthamiana<\/em> este preferat\u0103 \u00een agricultura molecular\u0103 deoarece produce volume mari de biomas\u0103 \u00een c\u00e2teva s\u0103pt\u0103m\u00e2ni \u0219i accept\u0103 cu u\u0219urin\u021b\u0103 vectori de expresie tranzitorie. Totu\u0219i, produc\u021bia nativ\u0103 de nicotin\u0103 reprezint\u0103 un obstacol persistent \u00een fabrica\u021bie. Alcaloidul este toxic pentru oameni la concentra\u021bii farmaceutice \u0219i se copurific\u0103 \u00eempreun\u0103 cu proteinele-\u021bint\u0103, necesit\u00e2nd procese costisitoare de filtrare \u00een mai multe etape pentru izolarea moleculelor terapeutice.<\/p>\n\n<p class=\"wp-block-paragraph\">\u201ePlantele de tutun pot fi utilizate \u00een biotehnologie ca platforme pentru producerea de vaccinuri sau alte produse farmaceutice, \u00eens\u0103 utilizarea lor este afectat\u0103 de prezen\u021ba nicotinei, care contamineaz\u0103 produsele \u0219i necesit\u0103 procesare pentru eliminare\u201d, a explicat Lichman.<\/p>\n\n<p class=\"wp-block-paragraph\">Prin utilizarea unor instrumente de editare genetic\u0103 \u021bintit\u0103 precum CRISPR pentru a dezactiva genele care codific\u0103 NaGT sau NicGS, oamenii de \u0219tiin\u021b\u0103 din agricultur\u0103 pot crea linii de tutun f\u0103r\u0103 nicotin\u0103. Aceste plante \u00ee\u0219i p\u0103streaz\u0103 cre\u0219terea vegetativ\u0103 rapid\u0103 \u0219i capacitatea de sintez\u0103 a proteinelor, elimin\u00e2nd complet contaminarea cu alcaloizi \u0219i reduc\u00e2nd costurile de produc\u021bie pentru terapiile derivate din plante.<\/p>\n\n<h2 class=\"wp-block-heading\">Proiectarea unor alcaloizi farmaceutici noi<\/h2>\n\n<p class=\"wp-block-paragraph\">Descoperirea stabile\u0219te, de asemenea, un cadru enzimatic pentru sintetizarea compu\u0219ilor medicinali care nu provoac\u0103 dependen\u021b\u0103. Natura modular\u0103 a sistemului cu patru enzime le permite cercet\u0103torilor s\u0103 introduc\u0103 molecule precursoare alternative \u00een cascad\u0103.<\/p>\n\n<p class=\"wp-block-paragraph\">\u00cen teste de demonstrare a conceptului, echipa de cercetare a ar\u0103tat c\u0103 \u00eenlocuirea analogilor de precursori a permis enzimelor s\u0103 produc\u0103 alcaloizi \u00eenrudi\u021bi, inclusiv nornicotin\u0103 \u0219i anabasin\u0103. Deoarece mul\u021bi alcaloizi deriva\u021bi din plante servesc drept structuri de baz\u0103 pentru medicamente destinate sistemului nervos central, terapii pentru durere \u0219i insecticide, adaptarea acestui mecanism enzimatic ofer\u0103 o metod\u0103 curat\u0103 de a produce compu\u0219i chimici complec\u0219i f\u0103r\u0103 sintez\u0103 industrial\u0103 la temperaturi ridicate.<\/p>\n\n<p class=\"wp-block-paragraph\">\u201eDeschide noi modalit\u0103\u021bi de a utiliza plantele de tutun \u00een scopuri benefice: nu \u00een \u021big\u0103ri, ci pentru medicamente \u0219i alte produse valoroase\u201d, a spus Lichman.<\/p>\n\n<ul class=\"wp-block-list\">\n<li>Rezultatele cercet\u0103rii sunt disponibile online \u00een revista <a href=\"https:\/\/www.nature.com\/articles\/s41467-026-72705-0\" target=\"_blank\" rel=\"noopener nofollow\">Nature Communications<\/a>.<\/li>\n<\/ul>\n","protected":false},"excerpt":{"rendered":"<p>Cercet\u0103torii de la Universitatea din York rezolv\u0103 un mister vechi de 200 de ani, cartografiind enzimele care asambleaz\u0103 nicotina pentru a permite culturi cu con\u021binut redus de nicotin\u0103.<\/p>\n","protected":false},"author":1,"featured_media":62925,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[184],"tags":[2790],"class_list":["post-62924","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-studii","tag-nicotine"],"acf":[],"_links":{"self":[{"href":"https:\/\/stagvape.com\/ro\/wp-json\/wp\/v2\/posts\/62924","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/stagvape.com\/ro\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/stagvape.com\/ro\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/stagvape.com\/ro\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/stagvape.com\/ro\/wp-json\/wp\/v2\/comments?post=62924"}],"version-history":[{"count":0,"href":"https:\/\/stagvape.com\/ro\/wp-json\/wp\/v2\/posts\/62924\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/stagvape.com\/ro\/wp-json\/wp\/v2\/media\/62925"}],"wp:attachment":[{"href":"https:\/\/stagvape.com\/ro\/wp-json\/wp\/v2\/media?parent=62924"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/stagvape.com\/ro\/wp-json\/wp\/v2\/categories?post=62924"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/stagvape.com\/ro\/wp-json\/wp\/v2\/tags?post=62924"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}