Mabinlin Explained

Mabinlin 1
Caption:Also known as: Mabinlin I, MAB I
Symbol:2SS1_CAPMA
Uniprot:P80351
Mabinlin 2
Caption:Also known as: Mabinlin II, MAB II
Symbol:2SS2_CAPMA
Uniprot:P30233
Pdb:2DS2
Mabinlin 3
Caption:Also known as: Mabinlin III, MAB III
Symbol:2SS3_CAPMA
Uniprot:P80352
Mabinlin 4
Caption:Also known as: Mabinlin IV, MAB IV
Symbol:2SS4_CAPMA
Uniprot:P80353

Mabinlins are sweet-tasting proteins extracted from the seed of mabinlang (Capparis masaikai Levl.), a plant growing in Yunnan province of China. There are four homologues. Mabinlin-2 was first isolated in 1983[1] and characterised in 1993,[2] and is the most extensively studied of the four. The other variants of mabinlin-1, -3 and -4 were discovered and characterised in 1994.[3]

Protein structures

The 4 mabinlins are very similar in their amino acids sequences (see below).

Chain A
M-1:
M-2:
M-3:
M-4:

Chain B
M-1:
M-2:
M-3:
M-4:
Amino acid sequence of Mabinlins homologues are adapted from Swiss-Prot biological database of protein.

The molecular weights of Mabinlin-1, Mabinlin-3 and Mabinlin-4 are 12.3 kDa, 12.3 kDa and 11.9 kDa, respectively.[3]

With a molecular weight of 10.4kDa, mabinlin-2 is lighter than mabinlin-1. It is a heterodimer consisting of two different chains A and B produced by post-translational cleavage. The A chain is composed of 33 amino acid residues and the B chain is composed of 72 amino acid residues. The B chain contains two intramolecular disulfide bonds and is connected to the A chain through two intermolecular disulfide bridges.[2] [4]

Mabinlin-2 is the sweet-tasting protein with the highest known thermostability,[5] which is due to the presence of the four disulfide bridges.[6] It has been suggested also that the difference in the heat stability of the different mabinlin homologues is due to the presence of an arginine residue (heat-stable homologue) or a glutamine (heat-unstable homologue) at position 47 in the B-chain.[3]

The sequences of Mabilins cluster with Napins .

Sweetness properties

Mabinlins sweetness were estimated to be about 100–400 times that of sucrose on molar basis, 10 times sucrose on a weight basis,[2] [3] which make them less sweet than thaumatin (3000 times) but elicit a similar sweetness profile.[7]

The sweetness of mabinlin-2 is unchanged after 48 hours incubation at 80 °C.[2]

Mabinlin-3 and -4 sweetness stayed unchanged after 1 hour at 80 °C, while mabinlin-1 loses sweetness after 1 hour at the same condition.[3] [8]

As a sweetener

Mabinlins, as proteins, are readily soluble in water and found to be highly sweet; however, mabinlin-2 with its high heat stability has the best chance to be used as a sweetener.

During the past decade, attempts have been made to produce mabinlin-2 industrially. The sweet-tasting protein has been successfully synthesised by a stepwise solid-phase method in 1998, however the synthetic protein had an astringent-sweet taste.[4]

Mabinlin-2 has been expressed in transgenic potato tubers, but no explicit results have been reported yet.[9] However, patents to protect production of recombinant mabinlin by cloning and DNA sequencing have been issued.[10]

See also

Notes and References

  1. Hu Z, He M . Studies on mabinlin, a sweet protein from the seeds of Capparis masaikai levl. I. extraction, purification and certain characteristics . Acta Botan. Yunnan. . 5 . 207–212 . 1983.
  2. Liu X, Maeda S, Hu Z, Aiuchi T, Nakaya K, Kurihara Y . Purification, complete amino acid sequence and structural characterization of the heat-stable sweet protein, mabinlin II . European Journal of Biochemistry . 211 . 1–2 . 281–7 . January 1993 . 8425538 . 10.1111/j.1432-1033.1993.tb19896.x .
  3. Nirasawa S, Nishino T, Katahira M, Uesugi S, Hu Z, Kurihara Y . Structures of heat-stable and unstable homologues of the sweet protein mabinlin. The difference in the heat stability is due to replacement of a single amino acid residue . European Journal of Biochemistry . 223 . 3 . 989–95 . August 1994 . 8055976 . 10.1111/j.1432-1033.1994.tb19077.x . free .
  4. Kohmura M, Ariyoshi Y . Chemical synthesis and characterization of the sweet protein mabinlin II . Biopolymers . 46 . 4 . 215–23 . October 1998 . 9715665 . 10.1002/(SICI)1097-0282(19981005)46:4<215::AID-BIP3>3.0.CO;2-S .
  5. Guan RJ, Zheng JM, Hu Z, Wang DC . Crystallization and preliminary X-ray analysis of the thermostable sweet protein mabinlin II . Acta Crystallographica Section D . 56 . Pt 7 . 918–9 . July 2000 . 10930844 . 10.1107/S0907444900005850 .
  6. Nirasawa S, Liu X, Nishino T, Kurihara Y . Disulfide bridge structure of the heat-stable sweet protein mabinlin II . Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology . 1202 . 2 . 277–80 . October 1993 . 8399391 . 10.1016/0167-4838(93)90016-K .
  7. Kurihara Y . Characteristics of antisweet substances, sweet proteins, and sweetness-inducing proteins . Critical Reviews in Food Science and Nutrition . 32 . 3 . 231–52 . 1992 . 1418601 . 10.1080/10408399209527598 .
  8. Kurihara Y, Nirasawa S . Structures and activities of sweetness-inducing substances (miraculin, curculin, strogin) and the heat-stable sweet protein, mabinlin . Foods and Food Ingredients Journal of Japan . 174 . 67–74 . 1997 . 2007-10-01 . https://web.archive.org/web/20130912205449/http://www.ffcr.or.jp/zaidan/FFCRHOME.nsf/7bd44c20b0dc562649256502001b65e9/ea044c8f392c31d5492568a20029dd20/$FILE/174-10.pdf . 2013-09-12 . dead .
  9. Xiong LW, Sun S . Molecular cloning and transgenic expression of the sweet protein mabinlin in potato tubers. . Plant Physiology . 1996 . 111 . 2 . 147 .
  10. US . 6051758 . patent. Samuel S.M.. Sun. Liwen. Xiong. Zhong. Hu. Hang. Chen. . Recombinant Sweet protein Mabinlin . 2000-04-18 .