[{"data":1,"prerenderedAt":758},["ShallowReactive",2],{"mdc--4pmajo-key":3},{"data":4,"body":5},{},{"type":6,"children":7},"root",[8,17,27,34,41,48,55,82,125,144,148,154,203,222,225,231,242,356,376,379,385,403,436,446,490,495,498,504,511,539,544,562,568,613,618,631,634,640],{"type":9,"tag":10,"props":11,"children":13},"element","h2",{"id":12},"d-and-l-amino-acids-complete-conceptual-overview",[14],{"type":15,"value":16},"text","🧬 D- and L-Amino Acids — Complete Conceptual Overview",{"type":9,"tag":18,"props":19,"children":20},"p",{},[21],{"type":9,"tag":22,"props":23,"children":26},"img",{"alt":24,"src":25},"Image","https://images.openai.com/static-rsc-3/ukgNgki7vZCX--_dgbrrWRIUh1DPM8md49mxcT6YlUOnEBAL_7qs84EqZI3Clwu25KTqwQToIW74ihJGsBpLU4LmGHSWjeq09Uqm6TCRhXo?purpose=fullsize&v=1",[],{"type":9,"tag":18,"props":28,"children":29},{},[30],{"type":9,"tag":22,"props":31,"children":33},{"alt":24,"src":32},"https://images.openai.com/static-rsc-3/FLqEyho8OB8sEONZUw-xuuSW_eU-e0MWo_Kh8SR7k2_qZYMSIbI6Szv_4Oz4vCv9ZcO5V0RNS8VI63D8NQnWr6R56mx7xz3EgFXT0bsVn1Y?purpose=fullsize&v=1",[],{"type":9,"tag":18,"props":35,"children":36},{},[37],{"type":9,"tag":22,"props":38,"children":40},{"alt":24,"src":39},"https://guweb2.gonzaga.edu/faculty/cronk/biochem/images/amino_acid.gif",[],{"type":9,"tag":18,"props":42,"children":43},{},[44],{"type":9,"tag":22,"props":45,"children":47},{"alt":24,"src":46},"https://www.researchgate.net/publication/339826729/figure/fig2/AS%3A867528674922497%401583846362426/Chirality-at-the-C-Carbon-Atom-of-Amino-Acids-Source-https-socraticorg.png",[],{"type":9,"tag":49,"props":50,"children":52},"h3",{"id":51},"_1️⃣-basic-structure-of-amino-acids",[53],{"type":15,"value":54},"1️⃣ Basic structure of amino acids",{"type":9,"tag":18,"props":56,"children":57},{},[58,60,66,68,73,75,80],{"type":15,"value":59},"All amino acids share the ",{"type":9,"tag":61,"props":62,"children":63},"strong",{},[64],{"type":15,"value":65},"same core scaffold",{"type":15,"value":67},", built around a ",{"type":9,"tag":61,"props":69,"children":70},{},[71],{"type":15,"value":72},"central carbon atom",{"type":15,"value":74},", called the ",{"type":9,"tag":61,"props":76,"children":77},{},[78],{"type":15,"value":79},"C-alpha (Cα)",{"type":15,"value":81},":",{"type":9,"tag":83,"props":84,"children":85},"ul",{},[86,97,107,115],{"type":9,"tag":87,"props":88,"children":89},"li",{},[90,95],{"type":9,"tag":61,"props":91,"children":92},{},[93],{"type":15,"value":94},"Carboxyl group (–COO⁻)",{"type":15,"value":96}," → gives amino acids their acidic nature",{"type":9,"tag":87,"props":98,"children":99},{},[100,105],{"type":9,"tag":61,"props":101,"children":102},{},[103],{"type":15,"value":104},"Amino group (–NH₃⁺)",{"type":15,"value":106}," → gives amino acids their basic nature",{"type":9,"tag":87,"props":108,"children":109},{},[110],{"type":9,"tag":61,"props":111,"children":112},{},[113],{"type":15,"value":114},"Hydrogen atom (H-alpha)",{"type":9,"tag":87,"props":116,"children":117},{},[118,123],{"type":9,"tag":61,"props":119,"children":120},{},[121],{"type":15,"value":122},"Variable side chain (R-group)",{"type":15,"value":124}," → determines the amino acid’s identity and properties",{"type":9,"tag":18,"props":126,"children":127},{},[128,130,135,137,142],{"type":15,"value":129},"👉 Because ",{"type":9,"tag":61,"props":131,"children":132},{},[133],{"type":15,"value":134},"four different substituents",{"type":15,"value":136}," are attached to C-alpha (except glycine), most amino acids are ",{"type":9,"tag":61,"props":138,"children":139},{},[140],{"type":15,"value":141},"chiral",{"type":15,"value":143},".",{"type":9,"tag":145,"props":146,"children":147},"hr",{},[],{"type":9,"tag":49,"props":149,"children":151},{"id":150},"_2️⃣-chirality-and-enantiomers",[152],{"type":15,"value":153},"2️⃣ Chirality and enantiomers 🪞",{"type":9,"tag":83,"props":155,"children":156},{},[157,167,179],{"type":9,"tag":87,"props":158,"children":159},{},[160,162],{"type":15,"value":161},"Amino acids exist in ",{"type":9,"tag":61,"props":163,"children":164},{},[165],{"type":15,"value":166},"two enantiomeric forms",{"type":9,"tag":87,"props":168,"children":169},{},[170,172,177],{"type":15,"value":171},"Enantiomers are ",{"type":9,"tag":61,"props":173,"children":174},{},[175],{"type":15,"value":176},"non-superimposable mirror images",{"type":15,"value":178},", like left and right hands",{"type":9,"tag":87,"props":180,"children":181},{},[182,184],{"type":15,"value":183},"These two forms are called:",{"type":9,"tag":83,"props":185,"children":186},{},[187,195],{"type":9,"tag":87,"props":188,"children":189},{},[190],{"type":9,"tag":61,"props":191,"children":192},{},[193],{"type":15,"value":194},"L-amino acids",{"type":9,"tag":87,"props":196,"children":197},{},[198],{"type":9,"tag":61,"props":199,"children":200},{},[201],{"type":15,"value":202},"D-amino acids",{"type":9,"tag":18,"props":204,"children":205},{},[206,208,213,215,220],{"type":15,"value":207},"Even though D and L forms have the ",{"type":9,"tag":61,"props":209,"children":210},{},[211],{"type":15,"value":212},"same atoms and bonds",{"type":15,"value":214},", their ",{"type":9,"tag":61,"props":216,"children":217},{},[218],{"type":15,"value":219},"3D arrangement differs",{"type":15,"value":221},", which has profound biological consequences.",{"type":9,"tag":145,"props":223,"children":224},{},[],{"type":9,"tag":49,"props":226,"children":228},{"id":227},"_3️⃣-how-to-determine-d-vs-l-configuration",[229],{"type":15,"value":230},"3️⃣ How to determine D vs L configuration 🔄",{"type":9,"tag":18,"props":232,"children":233},{},[234,236,241],{"type":15,"value":235},"To identify whether an amino acid is D or L, you must follow a ",{"type":9,"tag":61,"props":237,"children":238},{},[239],{"type":15,"value":240},"specific spatial procedure",{"type":15,"value":81},{"type":9,"tag":243,"props":244,"children":245},"ol",{},[246,263,323],{"type":9,"tag":87,"props":247,"children":248},{},[249,254,256,261],{"type":9,"tag":61,"props":250,"children":251},{},[252],{"type":15,"value":253},"Orient the molecule",{"type":15,"value":255}," so that the ",{"type":9,"tag":61,"props":257,"children":258},{},[259],{"type":15,"value":260},"H-alpha points away from you",{"type":15,"value":262},", hidden behind the C-alpha",{"type":9,"tag":87,"props":264,"children":265},{},[266,271,272],{"type":9,"tag":61,"props":267,"children":268},{},[269],{"type":15,"value":270},"Trace a path",{"type":15,"value":81},{"type":9,"tag":83,"props":273,"children":274},{},[275,292,307],{"type":9,"tag":87,"props":276,"children":277},{},[278,280,285,287],{"type":15,"value":279},"From ",{"type":9,"tag":61,"props":281,"children":282},{},[283],{"type":15,"value":284},"nitrogen (N)",{"type":15,"value":286}," → ",{"type":9,"tag":61,"props":288,"children":289},{},[290],{"type":15,"value":291},"carboxyl group (COO⁻)",{"type":9,"tag":87,"props":293,"children":294},{},[295,296,301,302],{"type":15,"value":279},{"type":9,"tag":61,"props":297,"children":298},{},[299],{"type":15,"value":300},"carboxyl group",{"type":15,"value":286},{"type":9,"tag":61,"props":303,"children":304},{},[305],{"type":15,"value":306},"first atom of the side chain (R)",{"type":9,"tag":87,"props":308,"children":309},{},[310,311,316,318],{"type":15,"value":279},{"type":9,"tag":61,"props":312,"children":313},{},[314],{"type":15,"value":315},"side chain",{"type":15,"value":317}," → back to ",{"type":9,"tag":61,"props":319,"children":320},{},[321],{"type":15,"value":322},"nitrogen",{"type":9,"tag":87,"props":324,"children":325},{},[326,331,333],{"type":9,"tag":61,"props":327,"children":328},{},[329],{"type":15,"value":330},"Observe the direction",{"type":15,"value":332}," of this path around C-alpha:",{"type":9,"tag":83,"props":334,"children":335},{},[336,346],{"type":9,"tag":87,"props":337,"children":338},{},[339,341],{"type":15,"value":340},"🔁 ",{"type":9,"tag":61,"props":342,"children":343},{},[344],{"type":15,"value":345},"Counterclockwise → L-form",{"type":9,"tag":87,"props":347,"children":348},{},[349,351],{"type":15,"value":350},"🔄 ",{"type":9,"tag":61,"props":352,"children":353},{},[354],{"type":15,"value":355},"Clockwise → D-form",{"type":9,"tag":18,"props":357,"children":358},{},[359,361,366,368,374],{"type":15,"value":360},"⚠️ This definition is ",{"type":9,"tag":61,"props":362,"children":363},{},[364],{"type":15,"value":365},"independent of optical rotation",{"type":15,"value":367}," (it does ",{"type":9,"tag":369,"props":370,"children":371},"em",{},[372],{"type":15,"value":373},"not",{"type":15,"value":375}," mean left- or right-rotating light).",{"type":9,"tag":145,"props":377,"children":378},{},[],{"type":9,"tag":49,"props":380,"children":382},{"id":381},"_4️⃣-relationship-between-dl-and-rs-configuration",[383],{"type":15,"value":384},"4️⃣ Relationship between D/L and R/S configuration",{"type":9,"tag":18,"props":386,"children":387},{},[388,390,395,397,402],{"type":15,"value":389},"The ",{"type":9,"tag":61,"props":391,"children":392},{},[393],{"type":15,"value":394},"absolute configuration",{"type":15,"value":396}," of the C-alpha carbon can also be described using ",{"type":9,"tag":61,"props":398,"children":399},{},[400],{"type":15,"value":401},"R/S nomenclature",{"type":15,"value":81},{"type":9,"tag":83,"props":404,"children":405},{},[406],{"type":9,"tag":87,"props":407,"children":408},{},[409,411,416,417],{"type":15,"value":410},"For ",{"type":9,"tag":61,"props":412,"children":413},{},[414],{"type":15,"value":415},"almost all amino acids",{"type":15,"value":81},{"type":9,"tag":83,"props":418,"children":419},{},[420,428],{"type":9,"tag":87,"props":421,"children":422},{},[423],{"type":9,"tag":61,"props":424,"children":425},{},[426],{"type":15,"value":427},"L-amino acids = S-configuration",{"type":9,"tag":87,"props":429,"children":430},{},[431],{"type":9,"tag":61,"props":432,"children":433},{},[434],{"type":15,"value":435},"D-amino acids = R-configuration",{"type":9,"tag":18,"props":437,"children":438},{},[439,441],{"type":15,"value":440},"🚨 ",{"type":9,"tag":61,"props":442,"children":443},{},[444],{"type":15,"value":445},"Exception: cysteine",{"type":9,"tag":83,"props":447,"children":448},{},[449,461,466],{"type":9,"tag":87,"props":450,"children":451},{},[452,454,459],{"type":15,"value":453},"Cysteine contains a ",{"type":9,"tag":61,"props":455,"children":456},{},[457],{"type":15,"value":458},"sulfur atom",{"type":15,"value":460}," in its side chain",{"type":9,"tag":87,"props":462,"children":463},{},[464],{"type":15,"value":465},"Sulfur has higher atomic priority than oxygen",{"type":9,"tag":87,"props":467,"children":468},{},[469,471],{"type":15,"value":470},"This flips the R/S assignment:",{"type":9,"tag":83,"props":472,"children":473},{},[474,482],{"type":9,"tag":87,"props":475,"children":476},{},[477],{"type":9,"tag":61,"props":478,"children":479},{},[480],{"type":15,"value":481},"L-cysteine = R",{"type":9,"tag":87,"props":483,"children":484},{},[485],{"type":9,"tag":61,"props":486,"children":487},{},[488],{"type":15,"value":489},"D-cysteine = S",{"type":9,"tag":18,"props":491,"children":492},{},[493],{"type":15,"value":494},"This is a classic exam-favorite exception.",{"type":9,"tag":145,"props":496,"children":497},{},[],{"type":9,"tag":49,"props":499,"children":501},{"id":500},"_5️⃣-biological-relevance",[502],{"type":15,"value":503},"5️⃣ Biological relevance 🧫",{"type":9,"tag":505,"props":506,"children":508},"h4",{"id":507},"ribosomal-protein-synthesis",[509],{"type":15,"value":510},"Ribosomal protein synthesis",{"type":9,"tag":83,"props":512,"children":513},{},[514,529],{"type":9,"tag":87,"props":515,"children":516},{},[517,522,524],{"type":9,"tag":61,"props":518,"children":519},{},[520],{"type":15,"value":521},"All ribosomally synthesized peptides and proteins",{"type":15,"value":523}," are made ",{"type":9,"tag":61,"props":525,"children":526},{},[527],{"type":15,"value":528},"exclusively from L-amino acids",{"type":9,"tag":87,"props":530,"children":531},{},[532,534],{"type":15,"value":533},"The ribosome ",{"type":9,"tag":61,"props":535,"children":536},{},[537],{"type":15,"value":538},"cannot incorporate D-amino acids",{"type":9,"tag":18,"props":540,"children":541},{},[542],{"type":15,"value":543},"This uniform chirality is critical for:",{"type":9,"tag":83,"props":545,"children":546},{},[547,552,557],{"type":9,"tag":87,"props":548,"children":549},{},[550],{"type":15,"value":551},"Protein folding",{"type":9,"tag":87,"props":553,"children":554},{},[555],{"type":15,"value":556},"Secondary structure formation (α-helices, β-sheets)",{"type":9,"tag":87,"props":558,"children":559},{},[560],{"type":15,"value":561},"Enzyme specificity",{"type":9,"tag":505,"props":563,"children":565},{"id":564},"occurrence-of-d-amino-acids",[566],{"type":15,"value":567},"Occurrence of D-amino acids",{"type":9,"tag":83,"props":569,"children":570},{},[571],{"type":9,"tag":87,"props":572,"children":573},{},[574,579,581],{"type":9,"tag":61,"props":575,"children":576},{},[577],{"type":15,"value":578},"D-amino acids do exist in nature",{"type":15,"value":580},", but:",{"type":9,"tag":83,"props":582,"children":583},{},[584,594,603],{"type":9,"tag":87,"props":585,"children":586},{},[587,589],{"type":15,"value":588},"They are ",{"type":9,"tag":61,"props":590,"children":591},{},[592],{"type":15,"value":593},"rare",{"type":9,"tag":87,"props":595,"children":596},{},[597,598],{"type":15,"value":588},{"type":9,"tag":61,"props":599,"children":600},{},[601],{"type":15,"value":602},"not produced by ribosomes",{"type":9,"tag":87,"props":604,"children":605},{},[606,608],{"type":15,"value":607},"They occur in ",{"type":9,"tag":61,"props":609,"children":610},{},[611],{"type":15,"value":612},"non-ribosomally synthesized peptides",{"type":9,"tag":18,"props":614,"children":615},{},[616],{"type":15,"value":617},"These systems are typically found in:",{"type":9,"tag":83,"props":619,"children":620},{},[621,626],{"type":9,"tag":87,"props":622,"children":623},{},[624],{"type":15,"value":625},"Certain bacteria",{"type":9,"tag":87,"props":627,"children":628},{},[629],{"type":15,"value":630},"Specialized bioactive peptides (e.g., antibiotics, signaling molecules)",{"type":9,"tag":145,"props":632,"children":633},{},[],{"type":9,"tag":49,"props":635,"children":637},{"id":636},"_6️⃣-big-picture-summary",[638],{"type":15,"value":639},"6️⃣ Big picture summary 🧠",{"type":9,"tag":641,"props":642,"children":643},"table",{},[644,663],{"type":9,"tag":645,"props":646,"children":647},"thead",{},[648],{"type":9,"tag":649,"props":650,"children":651},"tr",{},[652,658],{"type":9,"tag":653,"props":654,"children":655},"th",{},[656],{"type":15,"value":657},"Concept",{"type":9,"tag":653,"props":659,"children":660},{},[661],{"type":15,"value":662},"Key point",{"type":9,"tag":664,"props":665,"children":666},"tbody",{},[667,681,694,707,720,733,746],{"type":9,"tag":649,"props":668,"children":669},{},[670,676],{"type":9,"tag":671,"props":672,"children":673},"td",{},[674],{"type":15,"value":675},"Core structure",{"type":9,"tag":671,"props":677,"children":678},{},[679],{"type":15,"value":680},"C-alpha bonded to amino, carboxyl, H, and R",{"type":9,"tag":649,"props":682,"children":683},{},[684,689],{"type":9,"tag":671,"props":685,"children":686},{},[687],{"type":15,"value":688},"Chirality",{"type":9,"tag":671,"props":690,"children":691},{},[692],{"type":15,"value":693},"Most amino acids are chiral",{"type":9,"tag":649,"props":695,"children":696},{},[697,702],{"type":9,"tag":671,"props":698,"children":699},{},[700],{"type":15,"value":701},"D vs L",{"type":9,"tag":671,"props":703,"children":704},{},[705],{"type":15,"value":706},"Defined by spatial orientation, not optical rotation",{"type":9,"tag":649,"props":708,"children":709},{},[710,715],{"type":9,"tag":671,"props":711,"children":712},{},[713],{"type":15,"value":714},"Arrow method",{"type":9,"tag":671,"props":716,"children":717},{},[718],{"type":15,"value":719},"Counterclockwise = L, clockwise = D",{"type":9,"tag":649,"props":721,"children":722},{},[723,728],{"type":9,"tag":671,"props":724,"children":725},{},[726],{"type":15,"value":727},"R/S link",{"type":9,"tag":671,"props":729,"children":730},{},[731],{"type":15,"value":732},"L = S, except cysteine",{"type":9,"tag":649,"props":734,"children":735},{},[736,741],{"type":9,"tag":671,"props":737,"children":738},{},[739],{"type":15,"value":740},"Biology",{"type":9,"tag":671,"props":742,"children":743},{},[744],{"type":15,"value":745},"Proteins use only L-amino acids",{"type":9,"tag":649,"props":747,"children":748},{},[749,753],{"type":9,"tag":671,"props":750,"children":751},{},[752],{"type":15,"value":202},{"type":9,"tag":671,"props":754,"children":755},{},[756],{"type":15,"value":757},"Rare, non-ribosomal peptides only",1775084286592]