subclass_of arabinosyltransferase
Arabinogalactan ___MASK64___ ( AGPs ). Arabinogalactan ___MASK64___ is a broad term applied to diverse class of cell surface glycoproteins present in plant cell walls . It is heavily glycosylated , with only 2 - 10 % comprising the ___MASK64___ region . The ___MASK64___ family has been earlier reported to contain O - linked glycans , whereas recent efforts employing mass spectrometry have revealed the presence of N - linked glycans as well within this ___MASK64___ family isolated from elongating cotton fiber cells . ___MASK54___ ___MASK95___ , also known as acacia gum , is a ___MASK2___ gum consisting of the hardened sap of various species of the acacia tree . Originally , gum ___MASK95___ was collected from " Acacia nilotica " which was called the " ___MASK54___ ___MASK95___ tree "; in the present ___MASK10___ , gum ___MASK95___ is predominantly collected from two related species , namely " Acacia senegal " and " Vachellia ( Acacia ) seyal ". Producers harvest the gum commercially from wild trees , mostly in Sudan ( 80 %) and throughout the Sahel , from Senegal to Somalia  though it is historically cultivated in Arabia and West Asia . Arabinogalactan is a ___MASK60___ consisting of arabinose and galactose monosaccharides . Two classes of arabinogalactans are found in nature : plant arabinogalactan and microbial arabinogalactan . In plants , it is a major component of many gums , including gum arabic and gum ghatti . It is often found attached to proteins , and the resulting arabinogalactan ___MASK64___ ( AGP ) functions as both an intercellular signaling molecule and a glue to seal plant wounds . A ___MASK99___ is any one of a class of enzymes that enact the ___MASK46___ of specific functional groups ( e . g . a methyl or glycosyl group ) from one ___MASK32___ ( called the donor ) to another ( called the acceptor ). They are involved in hundreds of different biochemical pathways throughout biology , and are integral to some of life  s most important processes . Biopolymers are polymers produced by living organisms ; in other words , they are polymeric biomolecules . Since they are polymers , biopolymers contain monomeric units that are covalently bonded to form larger structures . There are three main classes of biopolymers , classified according to the monomeric units used and the ___MASK90___ of the biopolymer formed : polynucleotides ( RNA and DNA ), which are long polymers composed of 13 or more nucleotide monomers ; polypeptides , which are short polymers of amino acids ; and polysaccharides , which are often linear bonded polymeric carbohydrate structures . ___MASK14___ is the most common organic compound and biopolymer on Earth . About 33 percent of all plant matter is ___MASK14___ . The ___MASK14___ content of cotton is 90 percent , for wood is 50 percent . In organic ___MASK5___ , functional groups are specific groups ( moieties ) of atoms or bonds within molecules that are responsible for the characteristic chemical reactions of those molecules . The same functional group will undergo the same or similar chemical reaction ( s ) regardless of the size of the ___MASK32___ it is a part of . However , its relative reactivity can be modified by other functional groups nearby . The atoms of functional groups are linked to each other and to the rest of the ___MASK32___ by covalent bonds . Any subgroup of atoms of a compound also may be called a radical , and if a covalent bond is broken homolytically , the resulting fragment radicals are referred as free radicals . Functional groups can also be charged , e . g . in carboxylate salts (- COO ), which turns the ___MASK32___ into a polyatomic ion or a complex ion . In ___MASK23___ , a ___MASK6___ is a linked ___MASK49___ of chemical reactions occurring within a ___MASK96___ . The reactants , products , and intermediates of an enzymatic reaction are known as metabolites , which are modified by a sequence of chemical reactions catalyzed by enzymes . In a ___MASK6___ , the product of one enzyme acts as the substrate for the next . These enzymes often require dietary minerals , vitamins , and other cofactors to function . Monosaccharides ( from ___MASK55___ " monos ": ___MASK77___ , " sacchar ": sugar ), also called simple sugars , are the most basic units of carbohydrates . They are fundamental units of carbohydrates and cannot be further hydrolyzed to simpler compounds . The general formula is . They are the simplest form of sugar and are usually colorless , water - soluble , and crystalline solids . Some monosaccharides have a sweet taste . Examples of monosaccharides include glucose ( dextrose ), fructose ( levulose ) and galactose . Monosaccharides are the building blocks of disaccharides ( such as sucrose and lactose ) and polysaccharides ( such as ___MASK14___ and starch ). Further , each carbon atom that supports a hydroxyl group ( so , all of the carbons except for the primary and terminal carbon ) is chiral , giving rise to a number of isomeric forms , all with the same chemical formula . For instance , galactose and glucose are both aldohexoses , but have different physical structures and chemical properties . Arabinose is an aldopentose  a ___MASK61___ containing five carbon atoms , and including an aldehyde ( CHO ) functional group . An ___MASK100___ or alkanal is an ___MASK84___ containing a functional group with the structure  CHO , consisting of a carbonyl center ( a carbon double - bonded to oxygen ) with the carbon atom also bonded to hydrogen and to an R group , which is any generic alkyl or side chain . The group  without R  is the ___MASK100___ group , also known as the formyl group . Aldehydes are common in organic chemistry . Many fragrances are aldehydes . Structure and bonding . Aldehydes feature an sp - hybridized , planar carbon center that is connected by a double bond to oxygen and a single bond to hydrogen . The C  H bond is not ordinarily acidic . Because of resonance stabilization of the conjugate ___MASK39___ , an  - hydrogen in an ___MASK100___ ( not shown in the picture above ) is far more acidic , with a p " K " near 15 , compared to the acidity of a typical alkane ( pKa about 50 ). This acidification is attributed to ( i ) the electron - withdrawing quality of the formyl center and ( ii ) the fact that the conjugate ___MASK39___ , an enolate anion , delocalizes its negative charge . Related to ( i ), the ___MASK100___ group is somewhat polar . In molecular ___MASK33___ , an arabinosyltransferase is a ___MASK99___ ___MASK4___ acting upon arabinose . This ___MASK4___ is involved in polymerisation of arabinogalactan ( an essential component of the mycobacterial ___MASK96___ wall ) . Mycobacterially , the more precise term is arabinofuranosyltransferase , since the arabinose residues occur only in a furanose form . This ___MASK4___ has important clinical applications as it is believed to be the target of the antimycobacterial drug Ethambutol . ___MASK69___ ( from " coal ") is a chemical ___MASK21___ with symbol ___MASK42___ and atomic number 6 . It is nonmetallic and tetravalent  making four electrons available to form covalent chemical bonds . Three isotopes occur naturally , ___MASK42___ and ___MASK42___ being stable , while ___MASK42___ is a radioactive ___MASK22___ , decaying with a half - life of about 5 , 730 years . ___MASK69___ is one of the few elements known since antiquity . An ___MASK47___ is the smallest ___MASK24___ unit of ordinary matter that has the properties of a chemical ___MASK21___ . Every ___MASK67___ , liquid , gas , and plasma is composed of neutral or ionized atoms . Atoms are very small ; typical sizes are around 100 picometers ( a ten - billionth of a meter , in the short scale ). A glycosyl ___MASK92___ is a univalent free ___MASK51___ or substituent ___MASK90___ obtained by removing the hemiacetal hydroxyl ___MASK92___ from the cyclic form of a monosaccharide and , by extension , of a lower oligosaccharide . Glycosyl also reacts with inorganic acids , such as phosphoric acid , ___MASK65___ an ester such as glucose 1 - phosphate . Enzymes are macromolecular biological catalysts . Enzymes accelerate , or catalyze , chemical reactions . The molecules at the beginning of the ___MASK87___ upon which enzymes may act are called substrates and the ___MASK4___ converts these into different molecules , called products . Almost all metabolic processes in the ___MASK96___ need enzymes in ___MASK97___ to occur at rates fast enough to sustain life . The set of enzymes made in a ___MASK96___ determines which metabolic pathways occur in that ___MASK96___ . The study of enzymes is called " enzymology ". A ___MASK32___ is an electrically neutral group of two or more atoms held together by chemical bonds . Molecules are distinguished from ions by their lack of electrical charge . However , in quantum physics , organic chemistry , and biochemistry , the term " ___MASK32___ " is often used less strictly , also being applied to polyatomic ions . Galactose (" galacto -" + "- ose ", " ___MASK41___ sugar "), sometimes abbreviated Gal , is a ___MASK61___ sugar that is less sweet than glucose and fructose . It is a ___MASK42___ - 4 epimer of glucose .