תכונותיהן של החומצות
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תכונותיהן של החומצות האמיניות. חומצות אמיניות הידרופוביות. Alanine. Valine. A, Ala , alanine. Phenylalanine. Proline. Methionine. Leucine. Isoleucine. עתה סומן חלקה של חומצת האמינו שמשותף לכל הסוגים. יחודו של האלנין הוא הקבוצה המתילית שמקנה למולקולה אופי הידרופובי. אלנין. מתיונין.

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תכונותיהן של החומצות האמיניות

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5878289

תכונותיהן של החומצותהאמיניות

חומצותאמיניות הידרופוביות

Alanine

Valine

A, Ala, alanine

Phenylalanine

Proline

Methionine

Leucine

Isoleucine

עתה סומן חלקה של חומצת האמינו שמשותף לכל הסוגים

יחודו שלהאלניןהוא הקבוצההמתיליתשמקנה למולקולה אופיהידרופובי

אלנין

מתיונין

ואלין

לאוצין

לבסוף, אינכם צריכים לזכור את הפרטים לגבי כל חומצתאמינואלא לדעת על סמך נוסחאות המבנה, שינתנו לכם, מהן התכונות של כל אחת מחומצות האמינו.

פנילאלנין

איזולאוצין

פרולין


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חומצותאמיניות הידרופוביות

Alanine

Valine

PhenylalanineProline

Methionine

Leucine

Isoleucine

תכונותיהן של החומצותהאמיניות

V, Val, valine

Valine has two methyl groups so it's somewhat larger, rather more hydrophobic.

So here we have valine.


5878289

חומצותאמיניות הידרופוביות

Alanine

Valine

PhenylalanineProline

Methionine

Leucine

Isoleucine

תכונותיהן של החומצותהאמיניות

F, Phe, phenylalanine

This has this benzene ring, this unsubstituted benzene ring, very hydrophobic

And we have phenylalanine.


5878289

חומצות אמיניות הידרופוביות

Alanine

Valine

PhenylalanineProline

Methionine

Leucine

Isoleucine

תכונותיהן של החומצותהאמיניות

P, Pro, proline

Here's proline. Proline is a little different because it folds back onto the main chain of the amino acid. So, strictly speaking, proline is an imino acid instead of an amino acid but most biochemists don't make that distinction.

So proline has all of these CH2's, so it's very hydrophobic and it links back to the nitrogen of the amino group of the amino acid.


5878289

חומצות אמיניות הידרופוביות

Alanine

Valine

PhenylalanineProline

Methionine

Leucine

Isoleucine

תכונותיהן של החומצותהאמיניות

M, Met, methionine

methionine has a sulfur in here. It's one of two amino acids

with a sulfur, and again it's very hydrophobic

Methionine,


5878289

חומצות אמיניות הידרופוביות

Alanine

Valine

PhenylalanineProline

Methionine

Leucine

Isoleucine

תכונותיהן של החומצותהאמיניות

L, Leu, leucine

And then we have leucine and isoleucine.

Here's leucine, lot's of CH's, CH3's.


5878289

חומצות אמיניות הידרופוביות

Alanine

Valine

PhenylalanineProline

Methionine

Leucine

Isoleucine

תכונותיהן של החומצותהאמיניות

I, Ile, isoleucine

lots of CH2's and CH3's. So those are the hydrophobicamino acids.

Isoleucine is almost the same,


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תכונותיהן של החומצותהאמיניות

חומצות אמיניותטעונות

Aspartic acid (aspartate)

Glutamic acid (glutamate)

Lysine

Arginine

Histidine

D, Asp, aspartate

it just has a CH2 and a carboxyl group, and so that's an example of an acidic group.

aspartate, glutamate, lysine, arginine, histidine.

chargedamino acids;

Then we have the

So aspartate is the simplest,


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חומצות אמיניות טעונות

Aspartic acid (aspartate)

Glutamic acid (glutamate)

Lysine,

Arginine,

Histidine

תכונותיהן של החומצותהאמיניות

E, Glu, glutamate

Glutamate has basically the same thing, but with an extra CH2 in it.

See there are two CH2's and a carboxyl group


Chinese restaurant syndrome

Chinese restaurant syndromeתסמונת המסעדה הסינית

MSG (monosodium glutamate) is abused as a flavor enhancer in some restaurants, including some Chinese restaurants. People who are sensitive to MSG get a sensation like a clamp placed over their head and tightened. Fortunately, the sensation is temporary.

MSG (מונוסודיום גלוטמט) משמש להוספת טעם במסעדות מסוימות. בעיקר הוא נפוץ במסעדות סיניות. ישנם אנשים הרגישים לחומר זה ובעת האכילה נתקפים ברגישות המתבטאת בלחץ גדול בראשם שהולך וגדל. למזלם כאב הראש הוא זמני.

זהו מלחנתרנישל החומצההאמיניתח. גלוטמית, מונומר הנמצא כמרכיב כמעט בכל החלבונים.


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Charged amino acids

Aspartic acid (aspartate)

Glutamic acid (glutamate)

Lysine,

Arginine,

Histidine

תכונותיהן של החומצותהאמיניות

K, Lys, lysine

this has a nitrogen forming

this amino group at the end which is the basic group and

This is lysine the basic one,

this hydrocarbon chain


5878289

Charged amino acids

Aspartic acid (aspartate)

Glutamic acid (glutamate)

Lysine,

Arginine,

Histidine

תכונותיהן של החומצותהאמיניות

R, Arg, arginine

Arginine has these three nitrogens and here we can have a charge on this

Here's arginine.

guanidino group up here, so that's another basicresidue.


5878289

Charged amino acids

Aspartic acid (aspartate)

Glutamic acid (glutamate)

Lysine,

Arginine,

Histidine

תכונותיהן של החומצותהאמיניות

H, His, histidine

And then we have histidine. Histidine is very interesting because its pK is very close to the pH in the body, and so the charge on

this nitrogen here can be positive or negative depending on a variety of circumstances. And so this is a residue you often find at active sites of enzymes.


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תכונותיהן של החומצותהאמיניות

Polaramino acids

Serine

Threonine

Tyrosine

Cysteine

Asparagine

Glutamine

Tryptophan

S, ser, serine

Polar means that they interact well with water, so it's the opposite of hydrophobic. So these are ones which have groups on them which will form hydrogen bonds and interact well with water. So this is the list:

Serine has a hydroxyl group.

It's very simple just a methyleneand a hydroxyl group

serine, threonine, tyrosine, cysteine, asparagine, glutamine, tryptophan.

Let's move onto the polaramino acids.


5878289

Polar amino acids

Serine

Threonine

Tyrosine

Cysteine

Asparagine

Glutamine

Tryptophan

תכונותיהן של החומצותהאמיניות

T, Thr, threonine

Then threonine has a

methyl group in addition.


5878289

Polar amino acids

Serine

Threonine

Tyrosine

Cysteine

Asparagine

Glutamine

Tryptophan

תכונותיהן של החומצותהאמיניות

Y, Tyr, tyrosine

Tyrosine is a little more complex,

it has the benzene ring but it only has this

hydroxyl group out here making it polar.


5878289

Polar amino acids

Serine

Threonine

Tyrosine

Cysteine

Asparagine

Glutamine

Tryptophan

תכונותיהן של החומצותהאמיניות

C, Cys, cysteine

Cysteine is the other amino acid with a sulfur in it, and you

can see it again is very simple with that sulfur present.

And if we move onto cysteine.


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Polar amino acids

Serine

Threonine

Tyrosine

Cysteine

Asparagine

Glutamine

Tryptophan

תכונותיהן של החומצותהאמיניות

N, Asn, asparagine

this carbonyl and amine group here. This group does not ionize, so it is not charged. It is not acidic; it's not basic. It doesn't ionize in the body. It's polar because it interacts well with water, but it's not ionized.

And then we have asparagine.

This again has a single CH2 group and now it has


5878289

Polar amino acids

Serine

Threonine

Tyrosine

Cysteine

Asparagine

Glutamine

Tryptophan

תכונותיהן של החומצותהאמיניות

Q, Glu, glutamine

Same thing goes for glutamine.

Glutamine just has an additional CH2 group and again it has

this polar group at the end.


5878289

Polar amino acids

Serine

Threonine

Tyrosine

Cysteine

Asparagine

Glutamine

Tryptophan

תכונותיהן של החומצותהאמיניות

W, Trp, tryptophan

People usually put tryptophan in the group of polar amino acids, but personally I don't really agree with that.

It has this nitrogen here which can form hydrogen bonds which gives it some polar character, but in practice the non- polar nature of

these fused rings here actually is the dominant feature. So although tryptophan is often put in this group, it really has a mixture, as some of the others do, of properties.

So finally, the last one on here is tryptophan.


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תכונותיהן של החומצותהאמיניות

Glycine

G, Gly, glycine

is just a hydrogen atom. So this is basically just a very quick run-through of the amino acids, and as we talk about them more and see how they're used, you'll get more familiar with them and see how they work and see how their different properties are important. Today what I really wanted to get across was the nature of the forces between amino acids and the properties of the amino acids, which are important.

the simplest one of all, which I kept until last,

And then there's glycine,


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